Mar 202012

Fat loss is easy, all you have to do is eat fewer calories than you burn or so many people would have you believe. If you aren’t losing weight then you are either eating too much or not exercising enough.

Unfortunately the human body is a little bit more complicated than that and the calories in vs calories out model of fat loss has some serious flaws.

1. Food isn’t just caloires
One assumption calories in vs calories out makes is that the all the food we eat is converted into calories.

This assumes that whether you consume fat , protein or carbohydrate (macro-nutrients) it is all going to be used for energy and no other purpose. This is an incorrect assumption.

Protein is used for muscle repair. It is also found in our hair , nails , skin and brain and it can be converted into a number of hormones essential for the body to function.

Fat is used for insulation , it is used in cell membranes , it makes up part of the fatty sheath that surrounds nerve fibres, it helps with the absorption of some vitamins and is a key ingredient in hormones and other chemical substances that are vital for the body to function.

Carbohydrates are almost solely used for energy.

So depending on what you eat a certain amount of the macronutrients will be used for maintaining the cells in our body.A meal high in protein and fat will have a percentage of its potential calories used as building blocks for the body whereas a meal high in carbohydrates will be used solely for energy.

2. The numbers don’t add up.
According to the calories in vs out argument if I ate 100 less calories per day for a whole year I would lose 36500 calories or approx 4 kilos of fat. That sounds great you may think. What if I then kept this up for 10 years. I would then have lost a total of 40 kilos of fat. I currently weigh 67 kilos so I would then weigh 37 kilos!

Now 100 calories is approx 1 slice of bread . So I wouldn’t exactly be starving myself.

There have been a number of studies that have shown that people eating the same amount of excess calories put on vastly different amounts of weight. If the calories in vs calories out theory is correct then the amount of weight gain should be very predictable, instead it ranges enormously. Studies have also shown that it is possible to gain weight when eating less calories than what your body supposedly needs to maintain weight.

3. It takes energy to store energy.
Energy is required to convert food into a form of energy that can be stored by the body. The amount of energy required depends on whether it is carbohydrate, protein and fat and which scientific paper you read!

The macro nutrient composition of your meal will affect how many calories are burned in converting food into a storable energy source.

4. Different macro nutrients affect our bodies differently
Hormones such as insulin and glucagon affect our fat storage or fat usage systems. Other hormones like leptin and ghrelin affect our feeling of hunger and satiety and all of these hormones are influenced by what we eat. The primary influence is not the amount of calories that we eat but the type of food we eat.

If the calories in vs calories model out is correct then it shouldn’t matter if we obtain all of our calories from pure sugar or from lentils. If we eat less calories then we should lose fat. But sugar has a vastly different hormonal affect on the body than lentils.

5. Inaccuracies measuring calories
If the low calorie theory is correct then it is important to figure out how many calories we need to eat and how many we are burning per day. After all 100 calories extra and you will put on 4 kilograms in a year!

It is almost impossible to measure either the amount of calories you eat or the amount of calories you burn to anywhere near that degree of accuracy.

Any watch or machine that tells you how many calories you burn is making some pretty big assumptions. The amount of fat and muscle you have will affect your calorie usage, your genetics will also affect it, as will the amount of sleep you had, the temperature, the time of day, your stress levels and numerous other factors.

There are numerous calorie counters that will tell you how many calories are in a certain foods but the level of accuracy of these is very questionable. How many calories in an apple for example , a quick search on the net shows anything from 70-120 for the same size and type of apple.

If you are measuring everything you eat, and using a state of the art watch to measure your calories burned you are still only going to have an estimate that is maybe several hundred calories out. Clearly this isn’t a good way to go about losing fat.

6. All exercise is not the same
The more calories we burn during exercise the better. Right? Well what about exercise that doesn’t burn as many calories during exercise but raises your metabolism after your workout?

What about the hormonal response to exercise? Different exercise affects our hormones in different ways and our hormones effect fat storage , fat usage , muscle growth and numerous other bodily functions. High intensity cardio or weight training involving full body exercises will illicit a greater hormonal response than going for a walk. But if calories out is all that matters then whether we walk for 60 minutes or do weight training for 20 minutes as long as we burn the same amount of calories it shouldn’t make a difference. In the real world, weight training or high intensity interval training will have a far greater fat loss benefit than walking (comparing workouts burning the same amount of calories)

Why do some people lose weight when they count calories?
The primary reason some people are successful is that when people calorie count they choose healthier foods as they are often lower in calories. It isn’t the fewer calories that promotes the weight loss it’s the healthier food choices.

So if counting calories doesn’t work what should you do?
Whilst there is a raging argument going on between low carb, high carb, atkins, paleo, dukan , south beach or any of hundreds of other diets, I prefer to keep it simple. Eat a diet high in vegetables, a moderate amount of fruit, legumes, protein and good sources of fat, low in grains and cut out the processed stuff(its not really food). See here for my 6 essential tips for a healthy diet.

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  2 Responses to “Calories in vs Calories out : Is it really that simple?”

  1. Clear, concise and no BS! I’ve read a lot on this topic but this article lays it out as best I’ve seen. I did the calorie counting for about a year and while it worked, and I learned a lot about the calorie value of different foods, it often left me very hungry, requiring a lot of discipline. Now I just eat all natural foods, no processed foods at all, get all carbs from vegetables, no sugar and eat to satiety. My weight has stayed the same and I’m never craving.

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