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.