The less you sleep, the fatter you become

Tiredness makes us eat more, say scientists  

Volunteers who were sleep-deprived ate more than 500 additional calories per day

                                                                                               By TED THORNHILL

As if being tired from lack of sleep wasn’t punishment enough, now scientists say that not getting a good night’s rest could lead to obesity.

Researchers from the Mayo Clinic in Rochester, Minnesota, found that sleep deprived volunteers ate more calories.

The researchers studied 17 normal, healthy young men and women for eight nights, with half of the participants sleeping normally and half sleeping only two-thirds their normal time.

Participants ate as much as they wanted during the study.

‘We tested whether lack of sleep altered the levels of the hormones leptin and ghrelin [which are associated with appetite], increased the amount of food people ate and affected energy burned through activity,’ said Virend Somers, study author and professor of medicine and cardiovascular disease at the Mayo Clinic.

The sleep deprived group, who slept one hour and 20 minutes less than the control group each day consumed an average 549 additional calories each day.

Meanwhile, the amount of energy used for activity didn't significantly change between groups, suggesting that those who slept less didn't burn additional calories.

‘Sleep deprivation is a growing problem, with 28 per cent of adults now reporting that they get six or fewer hours of sleep per night,’ said Andrew D. Calvin, co-investigator, cardiology fellow and assistant professor of medicine at the Mayo Clinic.

The researchers stressed, though, that that while the study suggests sleep deprivation may be an important part and one preventable cause of weight gain and obesity, it was a small study conducted in a hospital's clinical research unit.

‘Larger studies of people in their home environments would help confirm our findings,’ Calvin said.

Chewing Reduces Food Intake and Elevates Fullness Hormone Levels

Chewing more can help you feel fuller

Mastication is the first step in ingesting food, but the effects of mastication on energy intake and gut hormones in both obese and lean subjects have not been extensively evaluated.

Researchers in China aimed to compare the differences in chewing activities between obese and lean subjects and to examine the effects of chewing on energy intake and gut hormone concentrations in both obese and lean subjects.

Sixteen lean and 14 obese young men participated in the current research. In study 1, they investigated whether the chewing factors of obese subjects were different from those of lean subjects. In study 2, they explored the effects of chewing on energy intake. A test meal consisting of 2200 kJ (68% of energy as carbohydrate, 21% of energy as fat, and 11% of energy as protein) was then consumed on 2 different sessions (15 chews and 40 chews per bite of 10 g of food) by each subject to assess the effects of chewing on plasma gut hormone concentrations.

The results show us that compared with lean participants, obese participants had a higher ingestion rate and a lower number of chews per 1 g of food. However, obese participants had a bite size similar to that of lean subjects. Regardless of status, the subjects ingested 11.9% less after 40 chews than after 15 chews. Compared with 15 chews, 40 chews resulted in lower energy intake and ghrelin (hunger hormone) concentration and higher and cholecystokinin (fullness hormone) concentrations in both lean and obese subjects.

In conclusion, interventions aimed at improving chewing activity could become a useful tool for combating obesity.

Why Lack of Sleep Could Be Making You Fatter

Sleepless nights don’t just ruin your mood the next day—they could also damage your waistline.

Sleepless nights don’t just ruin your mood the next day—they could also damage your waistline. According to new research in the August issue of the American Journal of Clinical Nutrition, sleep deprivation can cause people to pack on extra pounds.

Researchers at the New York Obesity Nutrition Research Center at St. Luke’s-Roosevelt Hospital found that sleep-deprived people seem to burn the same number of calories as the well-rested, but they consume about 300 more calories a day. Given that it takes just 3,500 calories to add a pound to your body, those calories can quickly turn into extra weight.

But there are several other reasons that sleep loss could lead to weight gain, says sleep disorder specialist Michael Breus. When we get too little shut-eye, our metabolism slows down to conserve energy. That slowdown triggers the release of the hormone cortisol, which increases appetite. Your body thinks it needs more energy, so it asks for more food.

In a vicious cycle, sleep loss also causes our bodies to release more ghrelin, another hormone that signals hunger, and less leptin, the hormone that tells your stomach that it’s full. With your hormones off-kilter, your body wants more food and lacks the sensitivity to know when to stop eating. Not to mention that being awake more hours gives you more time to snack.

“The later you’re up at night, the greater the likelihood that you’re going to eat,” Breus says. And “you’re more likely to eat high-fat, high-carb foods.”

One other contributing factor to such weight gain is that the body burns the most calories during REM sleep, a deeply restful phase. And less sleep means less time in REM.

For optimal health, experts say you should try to get 7.5 hours of sleep a night. If you have trouble sleeping, stick to a nightly routine, exercise during the day, banish worries to a journal, and keep pre-bedtime activities relaxing.

The Hunger Hormone By CAROL KOPP

The Hunger Hormone

The United States is the fattest nation on earth. Two-thirds of Americans are overweight. Nearly 59 million are considered obese, putting them at risk for diabetes, heart disease and high blood pressure. 

We’re all casualties of a battle between our genes and our fast food culture. And now, it turns out we may be casualties of a hormone called ghrelin. 

Ghrelin is the hunger hormone. It’s made in the stomach, and it tells the brain when it’s time to eat. Ghrelin doesn’t cause obesity, but scientists think taming it might help us get our scales back in balance. 

They’re also investigating an opposite hormone – PYY – that makes you feel full. 

So, as 60 Minutes II asked this spring, what if we could take a drug that would shut off our ghrelin or boost our PYY? 

In labs around the country, the race is on to find out. Correspondent Vicki Mabrey reports.

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The search for a billion-dollar solution to fat begins with mice. 

In a lab at the St. Louis Veterans Affairs Hospital, and in others like it, scientists are studying rodents to learn about the human appetite. They’re trying to find out why the hormone ghrelin makes a mouse so ravenous. 

We observed one illustration of ghrelin’s power. A mouse was injected with the hormone. Just 15 minutes later, he was absolutely wild for food, even though he’d already eaten enough to be full. 

Scientists are finding that ghrelin has the same power over people. 
That discovery was made in part through the experience of a man named Jim Rudolph, who used to weigh 460 pounds.

Taking a stroll along Seattle’s waterfront, Rudolph says, “I’m so happy to be able to walk like this today.” Not long ago, he couldn’t walk, drive or fit into one airplane seat. He also needed an electric cart to get around. 

Then, a pair of size 65 pants was a tight fit. He saved them to show 60 Minutes II that he can now fit into one of the pant legs.

Four years ago, Jim Rudolph underwent gastric bypass surgery. Such stomach reduction procedures are on the rise. Last year alone, 60,000 obese Americans went under the knife. 

He lost 195 pounds after his procedure. But that’s not surprising, since gastric bypass reduces the stomach by 95 percent. 

What is surprising, scientists say, is what Rudolph’s surgery revealed about appetite, and about the only hormone known to trigger it. The surgery seems to have killed the ability of Jim Rudolph’s body to produce ghrelin, or at least it put that function to sleep.

“I don’t seem to get really hungry,” he says. “It’s not necessarily hunger like the old hunger, going, you know, ‘Feed me.'”

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Dr. David Cummings, an endocrinologist at Seattle’s Veterans Administration Medical Center and the University of Washington, studied Rudolph and four other gastric bypass patients.

His team’s findings have captured the attention of scientists around the world, and have spurred the race to find a less drastic way than gastric bypass surgery to block ghrelin. 

Recently, Cummings showed off a test tube. “At the bottom of this tube is a little tiny fleck of stuff, which is pure dried ghrelin,” he says. 

What would happen to someone who ate that tiny bit of ghrelin?

“You’d want to eat,” says Cummings. “You’d want to eat right away.”

Japanese scientists discovered ghrelin in 1999. A year later, American researchers found that it drives appetite. 

”Ghrelin is the first and only yet-described appetite-stimulating hormone,” says Cummings, explaining that ghrelin is mainly created in the stomach, where it circulates in the blood, eventually sending a message to the brain to stimulate appetite. 

Cummings and his team studied ghrelin levels in obese dieters and in people of normal weight. They found that people who lost weight through dieting actually had elevated levels of ghrelin - not just occasionally, but day and night, whenever it was measured.

"Implication is that this is one of the ways in which the body fights against weight loss," says Cummings, which might help explain why millions of yo-yo dieters can’t keep the weight off.

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One of those dieters is Hillary Bargar Strackbein, a Connecticut prosecutor.

“I’m a lifetime member of Weight Watchers,” she says, “and I’m a successful Weight Watcher who lost about 90 pounds on Weight Watchers [and] gained it all back.” 

But that’s not all. She also went on the Jenny Craig diet: “I lost about 100 pounds, gained it all back ... then there's the the Atkins diet. I was on a grapefruit diet, soup diet." 

Basically, she’s been dieting pretty much all of her life.

Three years ago, Bargar Strackbein tipped the scales at 255 pounds. At that weight, she was ashamed to appear in court. 

Most recently, she put herself on a virtual starvation diet, eating only one 700-calorie meal a day. By living mostly on soy burgers and omelettes, and by exercising daily, Bargar Strackbein lost more than 100 pounds. 

Even so, her weight kept creeping back up, so she contacted Cummings about his research. 

What he told her was actually a relief: “He said, ‘The reason you feel your body’s trying to gain weight back is because it is. Your body is against you.’ It was the first time I ever saw a doctor or anyone say, ‘You’re right. I believe you. You’re not bingeing. You’re doing what you’re doing and it’s still not working right.'"

So, is Bargar Strackbein fighting a losing battle? Cummings says she may be: “I have to say that just playing the numbers, I would predict that she will not be able to maintain that weight loss, but I encourage her to try.”

He says that’s because each of our bodies has a genetic set point. In effect, your genes establish your weight range, and puts you in a body weight ballpark. 

"Within that ballpark, you can slide up or down about five or 10 percent, with dieting and exercise and the use of a few available medications we now have,” says Cummings. "And for most people, not much more than that is attainable or sustainable.”

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So, are we battling biology or bad habits? British obesity researcher Stephen Bloom says both. 

“We are machines designed to live through famine,” says Bloom. “In the days when we evolved, there would be a good harvest for six years and a bad harvest in the seventh year. And the only people who lived through the seventh year were the ones that were overweight. So, if you were able to watch your weight very nicely, you aren’t here anymore. We are survivors of the obese. All we need is a plentiful supply of food and we gain weight. That’s the way we are made.”

At London’s Imperial College, Bloom and his team are also studying ghrelin. But recently, they began experimenting with another hormone called PYY-336. You could almost call it the anti-ghrelin because this hormone makes you feel full. 

In Bloom’s study, hungry human volunteers were given PYY, and then offered an all-you-can-eat lunch. Researchers measured the leftovers, and found there was a lot left over. In fact, the test subjects ate one-third less for the full 24 hours after receiving PYY. 

The theory is, ghrelin goes to the brain and hunger sets in. "The ghrelin's disappeared after a meal, but the hormone to stop you eating, PYY, has risen in the bloodstream," says Bloom. "And as long as it's high, it stops you feeling hungry."

The evidence on ghrelin and PYY has so convinced Bloom that he’s practically given up on the common prescription of “eat less, exercise more.” He now says obesity has to be treated like any other illness, with medication. 

“The advice we give people does not seem to work,” he says, “so the answer is, as we have with blood pressure, take a tablet. As we have with cholesterol, take a tablet. So, I fear, with overweight, we have to damp down appetite. We can’t actually control ourselves. We have to accept that as a fact."

A diet expert advocating a magic pill for losing weight? “I hate it," says Bloom. "But I can’t think of anything better."

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A magic pill that is safer and more effective than what’s on the market now would be worth billions of dollars to pharmaceutical companies.

60 Minutes II got a rare look into a laboratory at Eli Lilly, where Dr. Mark Heiman, whose team first establishe that ghrelin made rodents hungry, is leading the search for a ghrelin blocker. 

He showed us a sample of just one of the substances being tested that may be a potential weapon for keeping weight off. 

The ingredients of that powder are top secret, of course. And with the stakes so high and competition so fierce, drug manufacturers almost never allow cameras in. 

Under a microscope, Heiman showed us ghrelin cells in the lining of the stomach. The fact that ghrelin is manufactured in the stomach, not in a riskier area like the brain, makes researchers hopeful that they can come up with a blocker.

But don’t look for that magic pill soon. “This is a long, long process,” says Heiman. “It would probably be about ten years before it’ll be in the pharmacist’s shelf."

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Doctors Heiman and Cummings hope to test the ghrelin blocker on people like Matt Heineman, 29, who suffers from a rare genetic disorder called Prader-Willi syndrome. 

People who suffer from Prader-Willi suffer from slowed development, severe obesity and insatiable appetite. Matt’s mother, Janalee Heinemann, says it’s a struggle to keep them alive. 

“They’ll just eat till they die. I mean, until they’re so obese they can’t breathe, that they have right-sided heart failure, that they have diabetes, etc.,” she says.

In other words, they literally eat themselves to death. 

It’s a condition, she says, that forces parents to act like jailers. To fight his uncontrollable urge to eat, Matt’s mother locked the refrigerator and cupboards, and monitored Matt wherever he went.

Even now, as an adult, Matt has to live a “safe house.” 60 Minutes II visited one outside St. Louis, where everything in the kitchen is kept locked and counselors search residents for unauthorized snacks and weigh them twice a day to make sure they’re not sneaking food. 

Cummings has found that ghrelin levels in people with Prader-Willi are off the charts: “We examined ghrelin levels in these people and found them to be among the highest that have yet been recorded in any humans.“ 

As one sufferer puts it, it feels like piranhas are in your stomach all the time. 

The thinking is that if a ghrelin blocker can cut the appetite of people with Prader-Willi syndrome, it could help others with less severe obesity problems.

But don’t get your hopes up yet. This isn’t the first time the Holy Grail of weight loss has appeared to be close at hand. Some earlier remedies have led to serious and sometimes deadly side effects.

The St. Louis researchers injecting mice with ghrelin are looking at other aspects of the hormone. Early evidence indicates ghrelin also may affect memory as well as growth and appetite. A ghrelin blocker could have an effect on all of those things.

So, is there ever going to be a magic pill that is going to make us as thin as we want to be?

“I don’t think that there’s ever going to be a single medicine that would prove to be the magic bullet for all people," says Cummings. "But I think there’s reason for hope that we may have, one day, half a dozen magic bullets that can be used in combinations to help people with their body weight in much more powerful ways than we now can do.”

The hormone that makes you fat By OLIVIA GORDON

The simple temperature test that could stop all the misery

Stepping on the scales, I gasped in shock. I weighed 12st - yet ten days earlier I had been 11st, and five weeks before that I was 9st. I had gained 3st in just over a month.

But my diet and activity levels hadn't changed - so the dramatic weight gain was inexplicable. I was 21, in my first term as a mature student at Brighton University, and over the previous few months, my whole body had seemed to go haywire.

Although my ballooning size was the most obvious change, I had other problems: my head felt full of cotton wool, I was exhausted, slurring my words and barely able to summon the energy to walk.

My hands and feet were oddly numb. I couldn't concentrate and my studies slipped. I had already been through a traumatic year. The previous Christmas, when I was 20, my boyfriend of four years, Paul, and our best friend, Jake, had been killed in a motorbike accident.

They had gone on holiday to Spain and one night I received a call telling me they had crashed after a night out and been killed outright.

Before Paul?s death, I had dropped out of my degree in Business Studies and started modelling clothes and working in bars and clubs in Brighton.

I?d never been under pressure to lose weight as a model, but after Paul?s death I lost my appetite.

Lonely, and realising life was short and I should make the most of it, I started going all-night clubbing and didn?t pay much attention to eating properly, so my body wasn?t in its healthiest state. I went off the rails.

One night, my heart started to pound. I couldn?t breathe and thought I was going to die. My friends took me to casualty, where doctors said I was having a panic attack.

I sat on the bed in hospital and caught sight of myself in a mirror. My neck was all swollen, but I was told it was fine and I was discharged.

I started having palpitations and panic attacks a couple of times a week and knew something was really wrong. At first I thought it was caused by the trauma of Paul?s death and I would just have to live with it.

Then I started sleeping the sleep of the dead ? I would lie down for a nap and wake up groggy 12 hours later, then pass out again.

But having been dismissed by the hospital, I didn't seek any further medical help and that September I went back to Brighton University to start a new degree in the History of Design, hopeful for a fresh start.

Yet here I was, halfway through the first term of my new degree course, suddenly four dress sizes bigger and feeling shattered and scared.

I was no longer the lively Chessy everyone knew: I had lost my confidence to the extent I could hardly go out. My friends and family were very worried about me.

My parents live in Malaga, Spain, and the last time they'd seen me was before I left for university. I was a size 8-10 and fit as usual, but that Christmas I came back a size 16 and three stone heavier and they were shocked to see me.

Mum later told me how we were eating dinner together one night when she saw my eyes glaze over. I sat with my fork in the air, staring into space. She said it looked as if my batteries had run down.

My parents believed me when I said I had an illness, but it was hard for them to be sure without a diagnosis - even I doubted I was ill sometimes.

I went to my GP, who did a blood test and told me there was nothing the matter with me. But I felt something was seriously wrong and saw a string of other doctors.

They all said I just needed to go on a diet and do some exercise. I cried, explaining that I wasn?t eating too much, but no one believed me.

I started to doubt myself, and did as the doctors suggested, going for a run on Brighton seafront. I managed about two minutes before I was too shattered to go on.

My size also meant I couldn?t apply for modelling jobs any more and my voice had got deeper, which meant my hopes of a singing career were also dashed.

I couldn?t fit into any of my clothes, and when my friends appeared shocked to see the new me, although I could understand their surprise, it really hurt my feelings.I just wanted to explain to everyone that I really was sick, and miserable.

I struggled on, until finally, at the end of the first year on my new degree, I was referred to a consultant. This time, my thyroid problem showed up in a blood test.

I have subsequently found out that because the range of readings for borderline patients is so wide, it is very much up to an individual doctor to make a definite diagnosis.

All my symptoms over the last year suddenly made sense. The thyroid gland regulates every metabolic process in your body, so with an under-active thyroid your body slows down - slow digestion and energy-burning leads to weight gain.

Vision, hearing, speech and mental processing abilities all wind down like clocks. Often thyroid problems run in families, but there is no history of it in mine.

My consultant explained that my thyroid could have been unbalanced by a traumatic event like the death of my boyfriend.

I also believe my unhealthy diet could have contributed to my illness, since that, as well as stress, is another known trigger.

I was prescribed hormone replacement medication, Thyroxine, to keep my thyroid ticking over. Sadly, there is no cure for an under-active thyroid and I will always have to take the medication, but I haven?t suffered any side-effects.

I understand that there are few problems if you take it long term - because it mimics the body?s own natural hormone. It took several months to start feeling better.

My mind got its sharpness back, my weight rebalanced at 11st and my panic attacks subsided. My neck is still swollen even after treatment, so my singing voice hasn?t come back, but I graduated from university, worked as a music and events producer, and then retrained as a journalist.

This year I started a fantastic job as a presenter on the radio station Talk Sport, where I can use my husky voice to my advantage!

Only now, ten years since I started treatment, am I finally getting back to health. I?ve been taking Thyroxine all this time and have to increase my dose every few years as my thyroid keeps slowing down.

I still have weeks when I feel tired and gain weight, and then I see my doctor and raise my dosage. I started on a low dosage and am still on a relatively moderate amount.

I've got my weight down to 9st 7lb, but I have to put a lot more care into my diet and exercise than most people.

It breaks my heart to think that someone may be going through what I did, just because some simple tests have not been tried, so I am supporting a campaign by Thyroid UK for doctors to use alternative tests, including checking urine and saliva.

Had someone recognised my symptoms rather than relying on inconclusive blood tests, it would have saved me years of illness.

There must be other people out there who are sick, tired and overweight, yet are being told by their doctors there is nothing wrong with them.

My advice, if you do notice any of the symptoms that I had, is to ask for a thyroid test. If it isn?t conclusive and you still feel ill, don?t give up.

Don?t think you are going mad, explore every avenue to get a diagnosis.

A SIMPLE TEMPERATURE TEST COULD STOP ALL THE SUFFERING

The thyroid gland, located in the neck, is part of the body?s endocrine system, which also includes the pituitary and adrenal glands, the pancreas and the testes.

This system regulates the body's hormones, controlling everything from growth to sex to (in the thyroid?s case) metabolism.

Hypothyroidism - or an underactive thyroid - produces a number of symptoms, the most common being weight gain, tiredness, hair loss, dry skin and lack of concentration.

Typically, weight gain is gradual, taking place over months or even years and sufferers find it difficult to shed weight by dieting.

The thyroid gland lies just below the Adam?s apple and secretes two hormones - thyroxine and triiodothyronine.

The first is called T4 and in the cells it is converted into the second hormone, T3.

It is T3, the active thyroid hormone, which is all-important and influences the speed with which cells work.

It regulates appetite, the glossiness of hair, whether the skin is dry or moist and above all, mental, physical and emotional energy. Too little and the body slows right down.

You?ll get depressed, moody and exhausted, have problems with your memory, put on weight, and lose hair. Constipation and a croaky voice are also signs of hypothyroidism.

Thyroid problems are diagnosed by a simple blood test which measures the level of TSH (thyroid stimulating hormone). The TSH test measures T4 on a scale of around 0.4 to 4 or 5.

Above 5, you will be diagnosed as having an underactive thyroid and will be prescribed thyroxine, a synthetic T4, which is taken in tablet form daily.

"It?s a very robust test," says Dr Mark Vanderpump, a consultant endocrinologist at the Royal Free Hospital, London. "If someone says they have an underactive thyroid and their TSH test is normal, then they haven't."

But this is where the debate starts. Some patient support groups and private practitioners argue that if someone has a reading between 2 and 4, then their thyroid is abnormal and such a patient would benefit from treatment.

They also argue that other diagnostic tests should be used in conjunction with the blood test - including, for instance, a temperature test, because low body temperatures can also be a symptom of an underactive thyroid.

Many doctors are reluctant to do this however, because thyroxine is a treatment for life and as such is expensive, particularly if it is not clear-cut whether the patient actually needs it.

A small amount of thyroxine will do no harm, they say, but if you give patients more than they need, there is a risk they may develop an abnormal heart rhythm and the bone-thinning disease, osteoporosis.

Thyroid UK, the support group set up in 1999, to increase awareness of the condition, is convinced that thyroid problems among young women are on the increase.

Its founder, Lyn Mynott, believes thousands of people, mainly women, are suffering from hypothyroidism - but are not getting adequate treatment.

Stress, a diet lacking in iron and fresh fruit and vegetables, and pollutants are the chief culprits, she says.

Dr Georges Mouton, a GP in Wimbledon with private clinics in Harley Street and Madrid, maintains that many of the major pollutants, such as dioxins and insecticides are well-known thyroid aggressors.

However, most doctors dismiss the connection with diet or pollutants and believe that it is simply convenient to use thyroid problems to explain away unwanted weight gain, depression or stress.

Moreover, some endocrinologists say that there is no evidence that hypothyroidism is on the increase - it?s just that people are having more blood tests, more abnormalities are being spotted and more people are blaming the thyroid.

According to Dr Prakash Abraham, consultant endocrinologist at Aberdeen Royal Infirmary: "It?s a fairly common condition. Doctors are checking it more, but there is nothing to suggest it is increasing."

Dr Colin Dayan, consultant endocrinologist at Bristol Royal Infirmary, says that around 5 to 10 per cent of women have an abnormal thyroid blood test, but it?s usually only very slightly abnormal and studies show that they would gain no benefit from taking thyroxine.

He stresses that only 1 in 100 have symptoms of hypothyroidism that affects their lives to the extent that they need treatment. 

BARBARA ROWLANDS.

Thyroid UK: www.thyroiduk.org British Thyroid Foundation: 01423 709 707; www.btf-thyroid.org

Are your hormones making you fat? By Susie Burrell

Are your hormones making you fat? By Susie Burrell

You eat well, exercise, yet your weight keeps climbing. As dietician Susie Burrell explains, it could be due to a hormone problem.

Sally was a slim kid and she remained thin throughout her 20s and 30s. By the time she'd hit her mid-40s, however, things had changed.

By this age, Sally was performing a supreme juggle. There were three children to take care of and a demanding full-time job.

Related: Why obesity is not your fault

Despite regular trips to the gym and following a healthy, low-fat diet, the scales showed a weight gain of 15kg.

No diet or exercise program seemed to be able to help Sally lose weight. In fact, the more she exercised, the more she seemed to weigh and she was tired, bloated and craving sugar.

I took one look at her and knew straight away — here was a client with insulin resistance.

Insulin resistance is a clinical condition in which insulin, the hormone secreted by the pancreas to control blood glucose levels in the body, is no longer working as efficiently as it should.

Over time, numerous factors, including a diet high in processed carbohydrates, a relatively inactive lifestyle and often genetics, affect insulin, which becomes less and less efficient at processing the glucose we consume in carbohydrate-based foods such as bread, cereals, fruit and sugars.

When insulin is not working properly, the body is forced to produce more insulin to process the same amount of glucose that we consume in food, to fuel the muscles and the brain.

The unfortunate thing when it comes to weight control is that the higher the amount of insulin you have circulating in your body, the harder it becomes to burn fat.

This means that if you have insulin resistance, you can be eating an extremely healthy diet and exercise regimen, but still be physically unable to lose weight.

In fact, as insulin is the central regulator of both glucose and fat metabolism in the body, when it is not working, the basic energy balance equation for weight loss (calories in versus calories out) simply does not hold true.

The situation Sally was facing — getting older, dealing with hormonal fluctuations and an inactive job, combined with a high-carbohydrate, low-fat diet, were likely to result in a further 10kg-20kg weight gain over 10 to 20 years.

Worse, if left unmanaged, insulin resistance will ultimately lead to Type 2 diabetes.

The good news is that if diagnosed early, insulin resistance can not only be managed, but even reversed with the right mix of diet and exercise training.

The body may show signs of insulin resistance in a number of ways. As resistance builds up over many months, if not years, these signs and symptoms can be subtle before becoming more noticeable.

Fatigue is common as glucose is not being taken to the cells as efficiently as it should be. Sugar cravings are common, too, as insulin and glucose levels fluctuate wildly during the day.

Perhaps the most powerful sign that insulin resistance may be present is in the way fat is deposited on the body.

Related: Ten tips to stop winter weight gain

Insulin likes to deposit fat around the abdominal area, which is why women (and men) with severe insulin resistance have a large belly and the reason a waist measurement greater than 80cm for a female may be a sign that insulin resistance is present.

If you are experiencing any of the symptoms of insulin resistance and find that you are constantly struggling with your weight, the best thing you can do is visit your GP or endocrinologist and have a glucose tolerance test to identify if insulin resistance is present.

Fitter, leaner in half the time

High Intensity Interval Training (HIIT)
5x Less Effective than Steady State Cardio???

By Tom Venuto, natural bodybuilder and author of Burn the Fat, Feed the Muscle

High Intensity Interval Training, or HIIT for short, has been promoted as one of the most effective training methods ever to come down the pike, both for fat loss and for cardiovascular fitness.
One of the most popular claims for high intensity interval training is that it burns “9 times more fat” than conventional (steady state) cardio. This figure was extracted from a study performed by Angelo Tremblay at Laval University in 1994. But what if I told you that high intensity interval training has never been proven to be 9 times more effective than regular cardio… What if I told you that the same study actually shows that high intensity interval training is 5 times less effective than steady state cardio??? Read on and see the proof for yourself.

In 1994, a study was published in the scientific journal Metabolism by Angelo Tremblay and his team from the Physical Activity Sciences Laboratory at Laval University in Quebec, Canada. Based on the results of this study, you hear personal trainers across the globe claiming that “HIIT burns 9 times more fat than steady state cardio.”

This claim has often been interpreted by the not so scientifically literate public as meaning something like this: If you burned 3 pounds of fat in 15 weeks on steady state cardio, you would now burn 27 pounds of fat in 15 weeks (3 lbs X 9 times better = 27 lbs).

Although it’s usually not stated as such, frankly, I think this is what some trainers want you to believe, because the programs that some trainers promote are based on convincing you of the vast superiority of high intensity interval training and the “uselessness” of low intensity exercise.

Indeed, higher intensity exercise is more effective and time efficient than lower intensity exercise. The question is, how much more effective? There’s no evidence that the “9 times more fat loss” claim is true outside the specific context in which it was mentioned in this study.

In order to get to the bottom of this, you have to read the full text of the research paper and you have to look very closely at the results.

13 men and 14 women age 18 to 32 started the study. They were broken into two groups, a high intensity interval training program (HIIT) and a steady state training program which they referred to as endurance training (ET).

The ET group completed a 20 week steady state aerobic training program on a cycle ergometer 4 times a week for 30 minutes, later progressing to 5 times per week for 45 minutes. The initial intensity was 60% of maximal heart rate reserve, later increasing to 85%.

The high intensity interval training group performed 25-30 minutes of continuous exercise at 70% of maximal heart rate reserve and they also progressively added 35 long and short interval training sessions over a period of 15 weeks. Short work intervals started at 10 then 15 bouts of 15 seconds, increasing to 30 seconds. Long intervals started at 5 bouts of 60 seconds, increasing to 90 seconds. Intensity and duration were progressively increased over the 15 week period.

The results: 3 times greater fat loss in the high intensity interval training group

Even though the energy cost of the exercise performed in the ET group was twice as high as the HIIT group, the sum of the skinfolds (which reflects subcutaneous body fat) in the HIIT group was three times lower than the ET group.

So where did the “9 times greater fat loss” claim come from?

Well, there was a difference in energy cost between groups, so in order to show a comparison of fat loss relative to energy cost, Tremblay wrote,

“It appeared reasonable to correct changes in subcutaneous fat for the total cost of training. This was performed by expressing changes in subcutaneous skinfolds per megajoule of energy expended in each program.”

Translation: The subjects did not lose 9 times more body fat, in absolute terms. But hey, 3 times more fat loss? You’ll gladly take that, right?

Well hold on, because there’s more. Did you know that in this oft-quoted study, neither group lost much weight? In fact, if you look at the charts, you can see that the HIIT group lost 0.1 kg (63.9 kg before, 63.8 kg after). Yes, the HIIT group lost a whopping 100 grams of weight in 15 weeks!

The ET group lost 0.5 kilograms (60.6 kg before, 60.1 kg after).

Naturally, lack of weight loss while skinfolds decrease could simply mean that body composition improved (lean mass increased), but I think it’s important to highlight the fact that the research study from which the “9 times more fat” claim was derived did not result in ANY significant weight loss after 15 weeks.

Based on these results, if I wanted to manipulate statistics to promote steady state cardio, I could go around telling people, “Research study says steady state cardio (endurance training) results in 5 times more weight loss than high intensity interval training!” Or the reverse, “Clinical trial proves that high intensity interval training is 5 times less effective than steady state cardio!”

Mind you, THIS IS THE SAME STUDY THAT IS MOST OFTEN QUOTED TO SUPPORT HIIT!

If I said 5 X greater weight loss with steady state, I would be telling the truth, wouldn’t I? (100 grams of weight loss vs 500 grams?) Of course, that would be misleading because the weight loss was hardly significant in either group and because interval training IS highly effective. I’m simply being a little facetious in order to make a point: Be careful with statistics. I have seen statistical manipulation used many times in other contexts to deceive unsuspecting consumers.

For example, advertisements for a popular fat burner claim that use of their supplement resulted in twice as much fat loss, based on scientific research. The claim was true. Of course, in the ad, they forget to tell you that after six months, the control group lost no weight, while the supplement group lost only 1.0 kilo. Whoop de doo! ONE KILO of weight loss after going through a six month supply of this “miracle fat burner!”

But I digress…

Back to the HIIT story – there’s even more to it.

In the ET group, there were some funky skinfold and circumference measurements. ALL of the skinfold measurements in the ET group either stayed the same or went down except the calf measurement, which went up.

The girths and skinfold measurements in the limbs went down in the HIIT group, but there wasn’t much difference between HIIT and ET in the trunk skinfolds. These facts are all very easy to miss. I didn’t even notice it myself until exercise physiologist Christian Finn pointed it out to me. Christian said,

“When you look at the changes in the three skinfold measurements taken from the trunk, there wasn’t that much difference between the steady state group (-6.3mm) and the HIIT group (-8.7 mm). So, much of the difference in subcutaneous fat loss between the groups wasn’t because the HIIT group lost more fat, but because the steady state group actually gained fat around the calf muscles. We shouldn’t discount simple measurement error as an explanation for these rather odd results.”

Christian also pointed out that the two test groups were not evenly matched for body composition at the beginning of the study. At the beginning of the study, the starting body fat based on skinfolds in the HIIT group was nearly 20% higher than the ET group. He concluded:

“So while this study is interesting, weaknesses in the methods used to track changes in body composition mean that we should treat the results and conclusions with some caution.”

One beneficial aspect of HIIT that most trainers forget to mention is that HIIT may actually suppress your appetite, while steady state cardio might increase appetite. In a study such as this, however, that can skew the results. If energy intake were not controlled, then some of the greater fat loss in the HIIT group could be due to lowered caloric intake.

Last but not least, I’d like to highlight the words of the researchers themselves in the conclusion of the paper, which confirms the effectiveness of HIIT, but also helps put it in perspective a bit:

“For a given level of energy expenditure, a high intensity training program induces a greater loss of subcutaneous fat compared with a training program of moderate intensity.”

“It is obvious that high intensity exercise cannot be prescribed for individuals at risk for health problems or for obese people who are not used to exercise. In these cases, the most prudent course remains a low intensity exercise program with a progressive increase in duration and frequency of sessions.”

In conclusion, my intention in writing this article wasn’t to be controversial, to be a smart-alec or to criticize high intensity interval training. To the contrary, additional research has continued to support the efficacy of HIIT for fat loss and fitness, not to mention that it is one of the most time efficient ways to do cardiovascular training.

My intentions for writing this article were four-fold:

1. To encourage you to question where claims come from, especially if they sound too good to be true.
2. To alert you to how advertisers might use research such as this to exaggerate with statistics.
3. To encourage the fitness community to swing the pendulum back to center a bit, by not over-selling the benefits of HIIT beyond what can be supported by the scientific research.
4. To encourage the fitness community, that even as they praise HIIT, not to condemn lower and moderate intensity forms of cardio.

As the original author of the 1994 HIIT study himself pointed out, HIIT is not for everyone, and cardio should be prescribed with progression. Also, mountains of other research has proven that walking (GASP! - low intensity cardio!) has always been one of the most successful exercise methods for overweight men and women.

There is ample evidence which says that obesity may be the result of a very slight daily energy imbalance, which adds up over time. Therefore, even a small amount of casual exercise or activity, if done consistently, and not compensated for with increased food intake, could reverse the obesity trend. High intensity interval training gets the job done fast, but that doesn’t mean low intensity cardio is useless or that you should abandon your walking program, if you have the time and if that is what you enjoy and if that is what’s working for you in your personal situation.

The mechanisms and reasons why high intensity interval training works so well are numerous. It goes way beyond more calories burned during the workout.

Sincerely,

Tom Venuto