When DID we start getting fat?

by Roger Highfield

Theories abound to explain why our waistlines started expanding, reports Roger Highfield

The introduction of the microwave, the birth of the supermarket and the end of the Second World War are among the reasons for the current obesity epidemic, according to experts who will today debate when precisedly the nation's waistline began to expand.

The microwave oven will be blamed by Jane Wardle, Professor of Clinical Psychology, University College London.

She explains. 'Population data in the UK show that obesity rates started to rise soon after 1984, and went up steadily at just under one percentage point a year. This same period saw the rapid spread of ownership of microwaves along with the first chilled, ready-meals appearing on supermarket shelves."

Eating got steadily cheaper, quicker, and more convenient, in the home and outside increasing our tendency to overeat and gain weight.

"Most of us, most of the time, match the energy we take in to the energy we expend," she said. "But people vary in their sensitivity to internal satiety [fullness] signals, and those with low satiety sensitivity can easily slip into positive energy balance.

In fact, most obese people don't overeat by a lot, but an energy excess of only 70kcals a day - no more than a ginger biscuit - adds up to 70lbs of extra weight in 10 years; enough to turn a slim 25 year old into an obese 35 year old.'

Professor Wardle will discuss her view with Dr Susan Jebb, Professor Ken Fox, and Professor Tim Lang at the Cheltenham Science Festival today (Wed 6 June), backed by The Daily Telegraph, which runs until Sunday (10 June 2007).

'Surprisingly the experts have all chosen different years and different triggers for the start of the obesity epidemic, illustrating the complexity of this problem and the fact that solving it has to be much more than telling people to eat less, do more.' Says Vivienne Parry, broadcaster who will chair the debate.

Tim Lang, Professor of Food Policy at City University also considers the changing way we eat as key, but pinpoints an earlier date - 1948 and the introduction of the supermarket.

'The year I choose is 1948 which is when the Co-op introduced the supermarket retail format to Britain, heralding the late 20th century food revolution in which prices have tumbled, car use rocketed, physical activity plummeted, cheap calories proliferated and the epitome of modernity was a tin shed stacked with 20,000+ items, and . . . the NHS was born, which picks up the pieces.'

Ken Fox, Professor of Exercise and Health Science, University of Bristol suggests July 5 1945, which marked the end of the war and the beginning of the end of manual effort. Professor Fox explains. 'The end of the war saw technology starting to replace physical effort in both work and leisure.

The TV arrived along with cars in big numbers. We stopped walking and cycling to work in large numbers. At the same time, we could not shake off our pre war values of earning the right to put our feet up. We have dramatically reduced our daily energy expenditure in the last 60 years and we have not managed to compensate by reducing our food and drink intake. We did not see the major effects until the early 80s because it takes a while to get fat (about 20-30 years) at the rates we probably have done.'

Dr Susan Jebb of the Medical Research Council Human Nutrition Research Centre Cambridge has pinpointed a more individual basis for the problem identifying the moment of conception as the key date. 'The nutritional status of the mother and later, the choice of breast or formula milk and the volume of milk provided, set the baby on its lifetime weight trajectory,'

Says Dr Jebb. 'Later parenting practices and peer group pressure reinforce the social value of foods and gradually we each begin to make our own decisions about our lifestyle - the die is cast.'

Other experts, who are due to launch a major report on obesity in October, suggest the following:

1986
Introduction of the IBM PC & daytime television

Tom Sanders, professor of nutrition, King's College Hospital "I would argue that in the UK prevalence rates started to increase across age groups in the 1980s. This was the time when day time TV started (BBC 1986, ITV 1987) and also the advent of the PC era with the debut of the IBM PC in 1981. The acceleration of obesity has been aided by Microsoft Windows."

1975
The advent of fast food outlets

Professor Peter Kopelmann, Dean Faculty of Health, University of East Anglia " Despite the inflationary spiral, both petrol and food costs remained relatively cheap. Car purchasing accelerated in the 1970s with many more homes acquiring either their first or second car, and we witnessed (in the UK) the advent of fast food outlets, initially the Wimpy but latterly McDonalds. My obesity research began in 1978 when the condition was relatively uncommon. When asked at the Hammersmith what my research interest was, my response of obesity was greeted with incredulity - "you must be crazy" Ah well, still "crazy after all these years"!

1947
The introduction of the Agriculture Act

Catherine Law, Centre for Paediatric Epidemiology and Biostatistics, Institute for Child Health "This was the year of 1947 Agriculture Act, the first UK policy to support subsidies and encourage mass production. It coincided with the postwar Baby Boom and a massive decline in breastfeeding rates. So a (large) generation of babies grew up without the protective effects of breastfeeding and with an (over) abundant food supply.

1954
The year commercial television began

Greg Maio, professor of psychology, University of Cardiff "This year began the trend of television being present in most UK homes and available most hours of the day. By the 1960s, this level of penetration coincided with a reduction of social and leisure pursuits, an increase in snack consumption and availability, and tipped the balance toward the "energy in" side of the obesity equation."

Why We Gain Weight When We’re Stressed—And How Not To

by Melanie Greenberg, Ph.D. in The Mindful Self-Express

Have you ever found yourself mindlessly eating a tub of ice cream while you brood about your latest romantic rejection or eating a hamburger and fries in front of your computer as you furiously try to make a work deadline? Perhaps you’re a busy mom, eating cookies in your car as you shuttle the kids back and forth to a slew of activities. Or you’re a small business owner desperately trying to make ends meet when you suddenly realize your waistline has expanded. If you recognize yourself in any of these scenarios, you’re not alone and it’s probably not your fault. Stress that goes on for a long period is a triple whammy for weight—it increases our appetites, makes us hold onto the fat, and interferes with our willpower to implement a healthy lifestyle.

Below are the four major reasons stress leads to weight gain and four great research-based coping strategies you can use to fight back.

Hormones

When your brain detects the presence of a threat, no matter if it is a snake in the grass, a grumpy boss, or a big credit card bill, it triggers the release of a cascade of chemicals, including adrenaline, CRH, and cortisol. Your brain and body prepare to handle the threat by making you feel alert, ready for action and able to withstand an injury. In the short-term, adrenaline helps you feel less hungry as your blood flows away from the internal organs and to your large muscles to prepare for “fight or flight.” However, once the effects of adrenaline wear off, cortisol, known as the “stress hormone,” hangs around and starts signaling the body to replenish your food supply. Fighting off wild animals, like our ancestors did, used up a lot of energy, so their bodies needed more stores of fat and glucose. Today’s human, who sits on the couch worrying about how to pay the bill or works long hours at the computer to make the deadline, does not work off much energy at all dealing with the stressor! Unfortunately, we are stuck with a neuroendocrine system that didn’t get the update, so your brain is still going to tell you to reach for that plate of cookies anyway.

Belly Fat

In the days when our ancestors were fighting off tigers and famine, their bodies adapted by learning to store fat supplies for the long haul. The unfortunate result for you and me is that when we are chronically stressed by life crises and work-life demands, we are prone to getting an extra layer of “visceral fat” deep in our bellies. Your belly has an ample supply of blood vessels and cortisol receptors to make the whole process flow more efficiently. The downside is that excess belly fat is unhealthy and difficult to get rid of. The fat releases chemicals triggering inflammation, which increases the likelihood that we will develop heart disease or diabetes. And it can make it more difficult to fit into those lovely jeans you splurged on, leading to more stress about money wasted! Unfortunately, excess cortisol also slows down your metabolism, because your body wants to maintain an adequate supply of glucose for all that hard mental and physical work dealing with the threat.

Anxiety

When we have a surge of adrenaline as part of our fight/flight response, we get fidgety and activated. Adrenaline is the reason for the “wired up” feeling we get when we’re stressed. While we may burn off some extra calories fidgeting or running around cleaning because we can’t sit still, anxiety can also trigger “emotional eating.” Overeating or eating unhealthy foods in response to stress or as a way to calm down is a very common response. In the most recent American Psychological Association’s “Stress in America:” survey, a whopping 40% of respondents reported dealing with stress in this way, while 42% reported watching television for more than 2 hours a day to deal with stress. Being a couch potato also increases the temptation to overeat and is inactive, which means that those extra calories aren’t getting burned off. Anxiety can also make you eat more “mindlessly” as you churn around worrying thoughts in your head, not even focusing on the taste of the food, how much you’ve eaten, or when you are feeling full. When you eat mindlessly, you will likely eat more, yet feel less satisfied.

Cravings and Fast Food

When we are chronically stressed, we crave “comfort foods,” such as a bag of potato chips or a tub of ice cream. These foods tend to be easy to eat, highly processed, and high in fat, sugar, or salt. We crave these foods for both biological and psychological reasons. Stress may mess up our brain’s reward system or cortisol may cause us to crave more fat and sugar. We also may have memories from childhood, such as the smell of freshly baked cookies,, that lead us to associate sweet foods with comfort. When we are stressed, we also may be more likely to drive through the Fast Food place, rather than taking the time and mental energy to plan and cook a meal. Americans are less likely to cook and eat dinner at home than people from many other countries, and they also work more hours. Working in urban areas may mean long, jammed commutes, which both increase stress and interfere with willpower because we are hungrier when we get home later. A University of Pennsylvania research study showed, in laboratory mice, that being “stressed” by exposure to the smell of a predator lead the mice to eat more high-fat food pellets, when given the choice of eating these instead of normal feed.

Less Sleep

Do you ever lie awake at night worrying about paying the bills or about who will watch your kids when you have to go to work? According to the APA’s “Stress in America” survey, more than 40% of us lie awake at night as a result of stress. Research shows that worry is a major cause of insomnia. Our minds are overactive and won’t switch off. We may also lose sleep because of pulling overnights to cram for exams or writing until the early hours. Stress causes decreased blood sugar, which leads to fatigue. If you drink coffee or caffeinated soft drinks to stay awake, or alcohol to feel better, your sleep cycle will be even more disrupted. Sleep is also a powerful factor influencing weight gain or loss. Lack of sleep may disrupt the functioning of ghrelin and leptin—chemicals that control appetite. We also crave carbs when we are tired or grumpy from lack of sleep. Finally, not getting our precious zzzz’s erodes our willpower and ability to resist temptation. In one study, overweight/obese dieters were asked to follow a fixed calorie diet and assigned to get either 5 and a half or eight and a half hours of sleep a night (in a sleep lab). Those with sleep deprivation lost substantially less weight.

How to Minimize Weight Gain When You’re Stressed

Exercise

Aerobic exercise has a one-two punch. It can decrease cortisol and trigger release of chemicals that relieve pain and improve mood. It can also help speed your metabolism so you burn off the extra indulgences.

Learn Mindful Eating

Mindful Eating programs train you in meditation, which helps you cope with stress, and change your consciousness around eating. You learn to slow down and tune in to your sensory experience of the food, including its sight, texture or smell. You also learn to tune into your subjective feelings of hunger or fullness, rather than eating just because it’s a mealtime or because there is food in front of you. A well-designed study of binge-eaters showed that participating in a Mindful Eating program led to fewer binges and reduced depression.

Find Rewarding Activities Unrelated to Food

Taking a hike, reading a book, going to a yoga class, getting a massage, patting your dog, or making time for friends and family can help to relieve stress without adding on the pounds. Although you may feel that you don’t have time for leisure activities with looming deadlines, taking time to relieve stress helps you to feel refreshed, lets you think more clearly, and improves your mood, so you are less likely to overeat.

Write in a Journal

Writing down your experiences and reactions or your most important goals keeps your hands busy and your mind occupied, so you’re less likely to snack on unhealthy foods. Writing can give you insight into why you’re feeling so stressed and highlight ways of thinking or expectations of yourself that may be increasing the pressure you feel. Writing down your healthy eating and exercise goals may make you more conscious of your desire to live a healthier lifestyle and intensify your commitment. Research studies have also shown that writing expressively or about life goals can improve both mood and health.

How to make yoghurt

You don't need any special tools to make yoghurt; it's a fairly easy undertaking, but you will need to gather a few bits and pieces first

Difficulty: Fairly easy; just needs a bit of kit
A yoghurt-maker is one of those kitchen gadgets no one really needs. Buy one if you like, but it will just give you one more thing to wipe grease off.

All you need to make yoghurt is something to heat liquid in, something to tell you its temperature, something to keep it warm, and something to hold it in the fridge. In other words, a saucepan, a thermometer, a wide‑mouthed vacuum flask or two and some jars. That, and you'll also need some "starter culture", bacteria that will convert plain milk into tangy, creamy deliciousness.

You can buy starter in dried form online or in health food shops, but the easiest source is wherever you already get your groceries. A small pot of live, plain, preferably organic yoghurt (check the label for "made with live cultures" or a list of "live bacteria") will contain enough bacteria to transform a litre or more of milk. While you're at it, pick up 500ml or a litre of milk – cows' or goats', pasteurised or UHT. Full-fat, semi, skimmed: they'll all make yoghurt, though of decreasing thickness. If you like your yoghurt extra-creamy, you could also invest in some powdered milk.

Back home, let the ready-made yoghurt come to room temperature, pour the milk into a saucepan and whisk in 25g powdered milk (if using) for every 500ml of milk. If this is pasteurised, heat it to 85C, stirring occasionally, then leave it to cool to about 46C (this process results in thicker yoghurt, as well as killing some unwanted bacteria). If UHT, simply warm it to 46C. Then whisk or stir in the live yoghurt – about 3 tbsp for every 500ml.

Before the mixture can cool, pour it into your warmed Thermos(es) and screw down the lid(s). Leave it for eight hours or so – or longer if you like your yoghurt thicker and stronger-tasting.

If it either tastes or smells off, chuck it away and start again. Otherwise pour it into clean jars and store it in the fridge. If you're happy with how it turns out, you can use a little of it as starter for your next batch. Freeze this if you won't be using it within the next few days.

Comments:

Unfortunately many brands of yoghurt on supermarket shelves contain little live probiotic or dead probiotic. Not to mention preservatives, stabilisers that don't improve the nutritional value of the food - additives are added to keep prevent the splitting of the yoghurt, to regulate the taste and to extend shelf life - not to help you.

Making your own yoghurt means you can dispense with the rubbish and get all the benefits out of the food by introducing live probiotics not the dead ones.

As you make one batch you can always use part of it as your starter culture for the next one - so it is a continuous cycle.

Go Easy On The Soy Sauce, Bro, It Could Kill You

by SCOTT HENSLEY



First, let's spoil this tale right away by telling you the 19-year-old man in Virginia who downed a quart of soy sauce on a dare survived.

It's a happy ending of sorts. But the guy had a close call. And you definitely don't want to try it.

While there's been quite a debate lately about whether the salt in the modern American diet is risky, there's no question that a massive amount of salt ingested quickly can lead to death.

In fact, suicide by soy sauce is not unknown in Asia. A 2011report in the Journal of Forensic and Legal Medicine describes the case of a 55-year-old woman diagnosed with depression. She died after drinking "a large quantity of shoyu (Japanese soy sauce)," doctors wrote.

Back in the early '90s, Mayo Clinic doctors reported on a 41-year-old man who died after swallowing a salty gargling solution. That case and a look at the medical literature up to that point led them to caution other doctors about using salty water to induce vomiting.

A salt dose ranging from 0.75 grams to 3 grams per kilogram of body weight can kill someone. A tablespoon of salt weighs about 15 grams, in case you're wondering.

If you're metrically challenged, just consider that the unnamed fellow in the report published online by the Journal of Emergency Medicine, weighed about 160 pounds and probably consumed around 170 grams of salt by drinking a bottle of soy sauce. That works out to a little more than 2 grams of salt per kilogram in his case.

After downing the soy sauce, he ran into trouble pretty fast. Within two hours he was in the emergency room at a local hospital. He was grinding his teeth and didn't respond to pain or verbal commands. His arms were stiff and at his side.

Doctors were worried about seizures and put him on drugs to control them. They also ran a tube from his nose into his stomach and sucked out some "brown material with scant streaks of blood," the report says.

The patient was transferred to a bigger hospital, the University of Virginia Medical Center in Charlottesville, within four hours of the soy sauce guzzling.

His blood sodium level measured at the medical center was the highest ever seen in an adult who survived such intoxication without lasting neurological problems, the medical paper says.

But the doctors didn't know if that would be the case. They opted for rapid treatment with water containing dextrose, a sugar, to dilute the sodium and encourage urination. The guy got six liters of IV fluid in half an hour. The sodium concentration in his blood fell, and he produced more than four liters of urine in short order.

The doctors took an aggressive approach even though there was a risk the man might experience brain swelling and other neurological side effects. They didn't see any.

5 Ways Sex Helps You Lose Weight -- and Keep It Off

Could heart-pounding fun between the sheets help you get slimmer faster? Definitely! But the reasons an active sex life promotes weight loss go beyond its potential to torch calories. They touch the core of this ultimate mind-body-soul experience. What the heck are we talking about? Consider these five ways sex helps get and keep you slim. Some will surprise you, and all will please you.

1. Sex blasts calories. Instead of burning a measly 70 calories per hour lying in bed together watching Netflix, invest in some highly enjoyable exercise. A mere 25 minutes of sex -- we're figuring 10 minutes of foreplay, 15 minutes for the main event -- burns 88 calories if you're a 150-pound woman, 106 calories for a 180-pound guy. That's the same energy you'd expend doing a light workout on a rowing machine or stationary bike. Trying out a fun new position that feels like an adults-only game of Twister will boost the burn rate a little. And going for a second round will, too. Arriving at the Big O gets your heart pounding as much as bounding up a tall flight of stairs.

2. Sex curbs carb and fat cravings. Regular sex can help keep levels of cortisol, the high-anxiety hormone, in check. That's good news, because too much cortisol boosts your appetite for high-fat, high-carb goodies and tells your body to store the extra calories around your midsection. A romp in the hay short-circuits cortisol's ill effects. Turns out sex dampens your body's "fight or flight" response to tension-provoking events. Intercourse, specifically, also calms your blood pressure, even when everything around you is going haywire. You remain serene instead of being possessed by an unstoppable craving for Twinkies. This stress buffer can translate into a slimmer midsection. 

3. Sex can double your fat loss. How? By helping you sleep like a baby. Skimping on sleep -- whether you're catching up on work or just tossing and turning -- undercuts your body's ability to shed fat, even if you're dieting! Indulging in some one-on-one pleasure before you say goodnight also releases oxytocin, the cuddle hormone that helps regulate slumber, too. Even a snuggly hug can nudge levels of this helpful hormone upward. That's good news for weight loss, because getting enough sleep can sharply increase the amount of fat you lose while dieting, according to one government study.

4. Sex can keep your diet on track. How? By improving your body image. Getting a self-esteem boost is one often-overlooked reason people have sex. What better proof of how appealing you are than an appreciative lover and a mutually satisfying romp!

And the rewards keep coming. Not only does sex improve your body image, but a better body image improves your sex life, too. Women who like themselves physically dive into more and better sex, regardless of the number on the bathroom scale. And when you do that, your appreciation for your body may spill over into healthier eating habits and a stronger commitment to exercise. Just remember, you don't need J-Lo's curves or Matthew McConaughey's sixpack abs to feel good about the way you look, with clothes or without. Focus on how good you and your partner can make each other feel and you might be surprised at how much healthier you start looking.

5. Good sex can make you slimmer and keep you that way. Already lost a few pounds? You may have noticed an uptick in sexual pleasure. Even modest weight loss can boost a guy's testosterone levels and reverse some erectile dysfunction. For women, trimming excess weight can enhance arousal, orgasms, and overall satisfaction. How can this keep you slim and trim? You have probably already heard (or know from experience) that maintaining a new, healthier weight is tougher than losing the pounds in the first place. If you keep this big but rarely noted bedroom benefit in mind the next time you're tempted to skip your morning walk or order the sausage and waffles with extra syrup, you'll not only keep on fitting into those skinny jeans, you'll also have even more fun when you take them off.

Source

Experiments to succeed, Calories do matter but the relationship is not linear to weight gain.

Failed diets, not failures but results of a kind and calories do count depending on the scale you work to.

Doing the same thing week in and week out can get stale but if it is a short term experiment it is fine.

When you have found out what works reasonably well then you need to adapt it to fit your life. If is breaks down then it is not ideal for long term use - but it is useful because it points you in the right direction. Knowing what does not work is equally valuable because it shows you where not to turn.

Each point is like part of the formula.

There are of course different formulas for different people.

The one formula that does work but often fails is because people can not stick to it. It either takes too long or is too complicated. A general but solid rule is to count calories.

I bet that gets a lot of hate mail. But let me explain. The relationship is not linear it is not simply calories in vs calories out because metabolic rate does not stay the same. If you look at the fattest people in the world and attempt to correlate calories with their weight often you find that they are actually eating far more calories than what their weight accounts for - they often should weight a lot more (sometimes 2 times more). There are various explanations such as their metabolic rate is faster, they can't digest that volume of food, they secretly throw it up, they have ice baths everyday, they lie about how many calories they actually eat, they are secret sumo wrestlers and the list goes on. The more probable explanations are their metabolic rate has increased, some of the food is not digested as well and food diaries may not be very accurate.

On the other hand people that say I am cutting 500 calories off my total daily energy expenditure so I should be losing 1 lb of fat a week. Now, the body has a set of priorities (often depending on circulating hormones) and can control its energy needs fairly well. If you consume less it can adjust for this small change - perhaps slow down metabolic rate very slightly.

Now not every calorie is the same this adds another variable. So carb, fat and protein calories are different. But when you have an excess of them what happens then - they get converted into fat or get stored as fat, if the the body has the facility and priority to do that. They also do not contribute to the same amount of fat generated. If you are not consuming enough calories then your metabolic rate can slow or your body must liberate energy from somewhere else - like your fat stores.

So to the people that say calories don't matter a simple experiment will prove other wise. On one scale you choose to consume double what you are currently consuming and on another you consume only half of what you are currently consuming for 8 weeks - what happens? Well you are most likely to gain some weight on consuming more and lose some weight if you are consuming less. (Of course the calories don't matter people didn't think you would try anything so extreme - perhaps adding on 10% more or taking away 10% might not matter because the body can often adjust and usually has its own small stores of nutrients. The body can account for small changes for instances storing up small amounts of vitamins, minerals, essential amino acids and essential fatty acids. What happens when you have an excess of these - does the body build up extra storage? Or how about depleting these stores to see what happens. Halving or doubling over a longer term will have more of an effect on adding surplus or depleting these small reserves and changing metabolism - again this is not a linear scale). If the calories don't matter then your weight WILL NOT CHANGE - can anyone prove weight will not change? The answer is the experts quickly suck back into their shells when big changes are mentioned - and try to evade this question. Just because something does not correlate perfectly does not mean it does not matter to say so can be misleading and make people extremely fat and lazy in counting calories.

Diets often vary the macros and control calories even if they do not tell you this. You need to be aware of this. Use calories as a guide - it is not the be all and end all but it is a very useful measure, especially with bigger changes in diet (especially when you are changing macros).

On some diets you will find you can eat more calories. On others less. However, on the longer term it is not possible to eat double and not gain any weight. Nor eat half and not lose weight. The percentage error tends to go up the fatter and thinner you get. So clearly there are points where the body is really trying to reduce fat storage and a point where the body is trying to hold onto fat. The general rule remains the same - even if it is not perfectly correlated.

Does Intermittent Fasting Really Work?

By Diana Kelly for Life by DailyBurn

There’s a new trend in dieting these days—not eating. Yup, “fasting” became a popular trend in the U.K. with The Fast Diet by Dr. Michael Mosley and has trickled over to the states in several variations, including The 8-Hour Diet by David Zinczenko, consulting editorial director at American Media, Inc. And while fasting itself is certainly not a novel concept (people have been doing it for religious reasons for hundreds of years), “intermittent fasting” as a weight loss method seems to be the new trend. But is it safe? And does it really work?We talked to fitness and nutrition expert JJ Virgin, bariatric surgeon Dr. Marina Kurian and Dr. John M. Berardi of Precision Nutrition to find out.

While there are different levels of intermittent fasting (IF) diets, two of the most buzzed about are The Fast Diet and The 8-Hour Diet. The Fast Diet, sometimes referred to the 5:2 diet, encourages people to eat normally five days per week, and trim calorie intake down to 500 to 600 calories total for two non-consecutive days. In terms of weight loss, participants can expect to shed about one to two pounds per week, says Dr. Mosley on his website. The 8-Hour Diet, on the other hand, limits the window of time for calorie consumption to eight hours per day, which is supposed to make the body burn fat and calories more efficiently. According to MensHealth.com (the brand author Zinczenko used to work for), The8-Hour Diet works on a cellular level and triggers the energy centers of the body’s cells (mitochondria) to selectively burn fat for energy. The diet is also said to reduce the amount of cancer-causing cell damage caused by the typical American diet, the site says.

Both diets claim that, in addition to helping participants lose weight (and keep it off), they’ll also help regulate blood sugar, possibly prevent diabetes, slow the ageing process, and prevent or minimize risk of heart disease. So far, these claims have only been supported by small human studies or animal studies. Our experts also noted that there isn’t much scientific research in support of IF diets as effective, long-term weight loss plans.

Still, that doesn’t necessarily mean they’re meritless, assuming you’re a healthy individual with realistic weight loss goals, some experts suggest. The positive aspect of these weight loss plans is that they challenge people to get in touch with hunger levels, says JJ Virgin, nutrition and fitness expert, author of The Virgin Diet. “Usually we’re eating because we are tired, thirsty or bored. Ask yourself why you’re eating again,” Virgin says.

Learning the difference between when you think you’re hungry and when you’reactually hungry was one of the biggest takeaways for John M. Berardi, MD, Chief Science Officer of Precision Nutrition and author of Experiments with Intermittent Fasting (based on his own experiments with various intermittent fasting plans over the course of six months).

“Trial fasting is a great way to practice managing hunger,” says Dr. Berardi. “It’s an essential skill for anyone who wants to get in shape and stay healthy and fit.” Though Dr. Berardi started off at a healthy weight, he lost 20 pounds in six months and reduced his body fat from 10 percent to four percent while maintaining most of his lean muscle mass, he says.

But is it dangerous?

While people should always check with their doctor before starting any weight loss plan, there are certain individuals who should steer clear of this type of diet, says Marina Kurian, MD, assistant professor of bariatric surgery at NYU Langone Medical Center. Those with insulin resistance issues, diabetics, pregnant women and people with low blood sugar should not try these plans, she says, as they could be dangerous to their health.

Virgin says this diet might also be problematic for women who are under chronic stress and have adrenal issues. “You’ll be stressing your body out more by following an intermittent fasting plan, which can lead to insomnia and possibly fertility issues,” Virgin says. Research has linked very low-calorie diets to chronic psychological stress and cortisol production, which has been shown to interfere with weight loss. The bottom line? If following this diet stresses you out or interferes with your sleep patterns, it could also impede weight loss.

Intermittent fasting could also be problematic for individuals with bingeing issues, or anyone who might have trouble controlling how much they’re eating on the non-fasting days. “Don’t let five of those days [or eight hours] be free-for-alls,” says Virgin. Both diets encourage eating wholesome, nutritious foods as often as possible during the times you’re not fasting.

Do fasting and exercise play nice?

As long as you’re adequately hydrated, Dr. Kurian says light to moderate exercise on lower-calorie days is generally safe, assuming you feel up to it. But if you don’t have the energy for exercise (or feel light-headed or dizzy), it may be best to save your strength for higher-calorie days. Plus, because exercise causes the body to burn through its glycogen stores, it’s important you’re able to refuel with a balanced meal or snack (including protein, carbs and fat), optimally within 30 minutes of working out.

If you already follow a regular exercise routine, it may be best to save your most intense workouts for days when you’re not fasting. After all, the goal should be to make the most of your workout session and that’s more likely to happen when you’re properly fueled with quality calories, Virgin says.

Bottom line: Is it worth trying?

As far as results go, regular fasting isn’t objectively better for losing body fat, Dr. Berardi says. While he says his IF experiments worked quite well, the intermittent fasting approach (bigger meals, less frequently) didn’t produce better fat loss than a more conventional diet approach (smaller meals, more frequently) might have.

And though it’s not dangerous to follow if you’re a healthy individual, Dr. Kurian says, she wouldn’t recommend this weight loss plan to her patients.

“You have to know what you’re capable of doing for a diet,” says Dr. Kurian. Instead, she recommends people aim to lose about a pound a week for long-term sustainable weight loss.

“Ask yourself if you can do this for life. It’s important to follow a weight loss plan you can maintain long term,” Dr. Kurian says. It’s also key to have a plan in place for the maintenance phase, after you’ve hit your weight loss goal. Otherwise, you’ll be more likely to regain the weight assuming following these fasting plans isn’t feasible for the rest of your life, she says.

Intermittent fasting can work, but it’s not for everyone—nor does it need to be, Dr. Berardi says. “In the end, IF is just one approach, among many effective ones, for improving health, performance and body composition.”