Calories in, Calories out

“Calories in, calories out,” has got to be one of the simplest to understand of all health statements. I mean, it makes such obvious sense. Calories go in, you burn off as many as you can and if there is any leftover the excess gets stored as fat.

The problem is that this is not how the body works. I mean, it is such a perversion of the truth as to beggar belief, but it does roll off the tongue quite easily and it is very easy to remember and that has gone a long way to making this untruth an underpinning of modern obesity control. Ironically, this complete misunderstanding of how the body works is also one the greatest causes of that self-same obesity epidemic. You see, when we focus on calories as the great demon of weight gain we miss the truth behind why everyone is suddenly gaining pounds like likes on a Facebook page. Worse still, trying to lose weight for anything more than a temporary few months using calories as your measuring stick will in fact almost guarantee you will gain the weight back… and probably a little extra with it.

So, if I am claiming that calories don’t make you fat (and I am), then what does?

Hormones. Hormones and your sensitivity or resistance to them make you fat.

I’ll give you 6 examples below which I hope will unveil the misdirection our current calorie obsession has had on our ability to control our weight and body composition and how this “calories in, calories out,” viewpoint is keeping us from focusing on what the real cause of weight gain is.

It is not that calories don’t have any effect on our body weight, they do, but they are so far down the list of things that cause weight gain as to be almost irrelevant to all but competitive athletes trying to shave off that last pound or two before competition. For example, the calories that make a person gain weight when they are insulin resistant may very well keep the very same person very lean when they are insulin sensitive. So, to focus on the calories before the sensitivity would make no sense at all…. But this is exactly what we have been doing for the last 60 years or so… About as long as the obesity epidemic has been spiraling ever upward. Maybe it is time to throw the calorie counter away and fix the body first.

Let’s start by first looking at where the “calories make you fat,” assumption comes from. The basic hypothesis is that if 1 lb of fat is 3500 calories and you eat 500 calories a day less than you normally eat, then every week you will be in a calorie deficit of 3500 by the end of the week and will therefore drop 1 lb of fat.  But, as just about everyone who has tried this knows, the weight loss only ever lasts a few weeks before grinding to a halt… The reason for this is quite simple, calories are not the problem, it is what the body does with the calories that is the problem, and it is your hormones which decided what your calories get to be used for. Here are a few of its options.

Increased heat production.

Better digestion.

Skin renewal.

Hair growth and condition.

Greater energy for exercise.

Improved immune function.

Eye health.

Brain power.

Muscle growth.

Muscle repair.

Bone maintenance.

Liver, kidney and other organ functions.

Fat gain.

So, as you can see from just this very short list of some of the things your body can do with the calories you eat, adding extra fat to your body is only one of the possibilities… It is our hormones and our sensitivity or resistance to them that decide where our calories go and it is our lifestyles and eating habits that set these sensitivity and resistance levels.

For example, if you train with weights, you will produce more Growth Hormone and testosterone and more of the calories you eat will be used for bone and muscle maintenance.  If you eat 6 times a day you will produce more insulin and you will store more calories as fat. If you only eat once or twice a day you will release more glucagon and burn more of your stored fat, even if the calories you are eating are the same as the person eating 6 times a day.

1.    Calories and Puberty

Before puberty boys and girls eat about the same number of calories each day and on average have roughly the same amount of body fat. After puberty, girls have about 50% more body-fat than boys, even though after puberty boys tend to eat 20% more calories per day than girls.

So why is this? Surly if calories make you fat and the boys are eating more than the girls then after puberty boys should be fatter than girls. But they are not.

The reason is that during puberty boys get a rapid increase of the hormone Testosterone and girls get a rapid increase in hormone estrogen. Testosterone channels more of the boy’s calories into muscle development, while estrogen pushes more calories into laying down the fat needed to widen the hips and develop the breasts. Extra calorie storage is also needed by women to ensure a growing fetus can get access to a constant supply of food, even in times of food scarcity.

As you can see, in puberty it is hormones and what they do with calories and not the calories themselves that make you gain fat or muscle.

2.    The Sam Feltham Experiment

To test the, calories in calories, out hypothesis, a Master Trainer called Sam Feltham, did an experiment on himself with some serious overeating.
He started by eating 5800 calories a day for 21 day using a low carbohydrate, high fat diet.
The result was a gain of 1.3 kg in body weight and a drop of 2.5 cm from his waist…. In other words, he lost body fat.
He then repeated the experiment, eating 5800 calories a day using a high carbohydrate, low fat diet.
The result was a gain of 7.1 kg in body weight an increase 9.14 cm in his waist. In other words, he got fat…So why is this?If calories make us fat and Sam was eating a conservative 2800 k-cals a day over his limit, (Assuming he was eating about 3000 a day normally) then he should have gained about 18 lb (7-8 kg) of fat no matter what kind of diet he was on… but he didn’t.  He only gained the body-fat when he was eating the carbohydrates. The reason is that carbs spike insulin (our fat storage hormone) and fat doesn’t. So, more storage hormone = more body fat and not more calories. You can read Sam’s Experiment in all its detail by clicking here.

3.    The thin People paradox

We all know people who seem to eat a lot of food and never put on a pound.  For example, I have a very good friend how stayed with me for large parts of our childhood. And even when we weren’t sharing the same house, we hung around together all the time. Our diets were the same, our environments were the same; we played together and later trained together, so our activity levels were the same… But my friend was always lighter than me. He always had a much harder time gaining weight than I did and he always lost weight a lot easier than I did. Decades later this is still very much the case.

So why is this?

There are several possibilities here. It could be a genetic component, it could be that I had more access to sugar when I was younger than he did, and so became more insulin resistant from an early age. He could have more leptin receptors than I do… No matter which of these or any other reasons is true, the result is still the same, with equal calories I gain weight faster because my hormone set up had given me a higher body fat set point.
If the calories are the same but the result is different it can only ever be what the body does with the calories that is different and as I have shown already, that is down to our hormones and our sensitivity to them.

4.    The women’s Health Initiative Dietary Modification Trial.

This was the largest ever study done on weight loss in women. It was a 7.5-year study involving over

50,000 women and it published its results in 2006.

One third of the women were put on a diet education course and instructed to cut their fat by 20%, eat 5 servings of fruit and veg a day, eat 6 serving of carbohydrate a day and to cut their calories from their current average of 1788 a day to an average of 1446 a day. They were also instructed to increase their daily activity by 14%

Again, if you follow the belief that calories make you gain weight and cutting them leans you out then a study of this length should have been the very proof you are after.

The results?  By the end of year 1, the women had lost on average 4-5 pounds. By the end of year 2 they had regained most of that weight. By the end of the 7.5-year trial, there was no discernible difference in weight between the dieting group and the control group, (who had made no changes to either their diets or activity levels).

What’s more is that the dieting group increased the size of their waists and waist to hip ratios… Which means they actually got fatter.

So why was this?

I could easily write a whole piece on this one case alone but I will break it down as easily as I can because this case proves a pivotal point you need to take away with you. That, cutting calories only ever gives short term results and will almost always result in the weight being gained back, normally with a few extra pounds, and a greater percentage of body fat to go with it.

The reason this happens is because your body is far more than just a calorie counting machine. It is a living breathing organism designed to adapt to change when it observes it and to scale down its activities accordingly.

Your hormone levels, (in this case leptin, insulin, thyroid hormones and Ghrelin) create a set point for your body weight and body fat levels. When you cut your calories (let’s say by 500 per day, as this is a common approach at the moment), your body simply lowers its own output by 500 calories a day to deal with the lower incoming calories while doing its best to protect that set point dictated by your hormone levels. This starts to happen in the first few weeks and by 4 to 6 weeks, the new lower calorie intake will not produce any further weight loss. What’s worse is that by now the body will also have started to up Ghrelin production, the hunger hormone, to try and get you eating more.  The full data can be found here.

5.    Diabetics

One of the early signs of Type 1 Diabetes is sudden weight loss. This happens despite there being no difference in calorie intake.

The reason.

Type 1 diabetes is a result of an autoimmune condition which attacks the beta cells on the pancreas where insulin in made. No insulin means no storage, no storage means dangerous amounts of weight loss. For anyone wanting to know more about diabetes click here.

6.    The Obese boy with the damaged Hypothalamus

In 1890 Dr. Alfred Froohlic noticed that a boy he was treating with a lesion on his brain was suddenly gaining a lot of weight. The damage the boy had was to the hypothalamus, a small pea sized gland at the center of the boy’s brain. This apparent, gland, body-fat connection, led Dr. Alfred Froohlic on a career of study which culminated in another gland to body-fat condition in women being named after him, Fröhlich’s syndrome.

Although at that time the exact reason why this damage to the hypothalamus  might cause the boy to gain weight was unknown, we now know that the hypothalamus uses the hormone leptin to determine how much fuel the body has in storage as fat and based on this information the hypothalamus then sets our metabolic rate and hunger levels. A bad diet or eating excessive meals a day can desensitize our hypothalamus to leptin. Poor leptin signalling means dis-regulation of weight and energy levels without any changes in calories needed.

Along with insulin, Leptin, or rather our bodies ability to read it, is another crucial factor as to how many of the calories we eat are freed up to fuel biological process within the body and how many are sent to be stored as body fat.

Poor leptin sensitivity means more body fat. More Leptin sensitivity means a leaner more energetic body.

To learn about more of the work of Dr. Alfred Froohlic click here.


As we can see from all 6 of the examples above calories are very rarely the cause of weight gain,

unless the body has become resistant to the many hormones that control where those calories go. Learn to fix your hormone resistance and you can stop counting calories, finally shed that unwanted body-fat and keep it off. More importantly you will also greatly improve your overall health.

While the process for fixing your hormone resistance can be a little different from person to person a good place to start is by removing all processed foods from your diet, reducing carbohydrate intake (especially sugar), increasing fat intake and reducing the frequency of meals.

To learn more about how you might go about doing this consider joining our Forever Lean program or ask about our  personal health coaching program by mailing Aaron at

Coach Aaron