Why eat less and move more is useless advice
We all know it: to lose weight we all need to eat less and/or excercise more. Even Stephen Hawkings said so : "We eat too much and move too little". Givin the fact that Hawkings cannot move at all, while he seems to be almost anorexic, this comment is more than just a little ironic. Because the thing is this: while you indeed need to be in a caloric deficit to become smaller the idea that you can ONLY do this by moving more and eating less is overly simplistic and woefully incomplete. It's nothing more of a restatement of the first physics law of thermodynamics (conservation of energy) in the field of nutrition. But humans are not physical objects, they are complex biological beings instead.
There is an apt analogy here: suppose you want to get rich and your wealth advisor says to you: the only way to become rich is to earn more money than you spend. Technically he would be completely correct of course. Still the only thing you can do is to throw the advice in the dustbin and to fire your advisor. What you want to know of course is HOW you can earn more money than you expend. Advice on setting up a business for instance, or advice on where to invest your money in.
Yet over the past three decades that's the same kind of advice we have been given when it comes to weight loss and obesity. Don't eat too much, don't each too much fat (because it has more calories than carbs or protein) and exercise so that the calories you take in are less than the calories you expend. This also is technically correct. After all, when calories in exceeds calories out, weight gain will result (because energy cannot be destroyed, according to the laws of thermodynamics, excess energy will be stored as fat). Nevertheless, as shown by the skyrocketing obesity rates, this advice seems to be completely worthless and irrelevant.
There are several reasons why this is the case. First of all, the energy out side of the calorie equation (change is body stores equals energy in minus energy out) entails much more than just exercise. In fact, unless you do it intensively for hours each day, exercise will be just a small part of your total energy expended. This is why exercise will only work for people who have the willpower and the time to do it every day and for the rest of their lives. Besides, the more you exercise the more likely it will be that you eat more, partly cancelling out the effects of your phyiscal endeavours. More importantly, research has shown that people who exercise more spontanously reduce their other daily physical activities. They will start taking the elevator instead of the stairs for instance, again partly cancelling out the results of exercise. This so-called non-exercise activity thermogenesis (NEAT) is also a major part of the energy out side. The other major part is your basic resting metabolism. A decrease in your metabolism obviously will hinder your efforts at weight loss, while a fast metabolism will make it much easier to loose weight, and keep if off. Unfortunately, you don't have much of an impact on your basic metabolism. The last part of your energy out is what is called the thermogenic effect of food. Some types of food require a higher amount of energy to digest than other. Protein for instance needs to be dissasembled into it's individual amino acids and then reassabled into full proteins. This costs a lot of energy: up to 35% of your protein intake is wasted while being digested. In other words, protein intake also raises energy output, so that the same amount of calories of protein will be less fattening than the same numer of calories coming from fat or carbohydrates.
This brings us to another problem with the conventional wisdom namely that the amount and type of calories you eat will have an impact on the calories you expend (and the other way around), in many different ways. Or, as scientists would say, calories in and calories out are not independent variables. As we have seen, increasing protein intake will also increase the number of calories which are burned. On top of that, protein also increases muscle mass, and therefore also will underpin your resting metabolism, which depends partly on the amount of muscle you have. Or take this example, which I got from Paul Jaminet, author of the Perfect Health Diet. Swichting from polyunsatuarated fat to saturated fat will make you feel more energetic. As a result you will likely increase you daily activity and exercise more, raising energy output, and automatically establishing a caloric deficit. High-protein diets and high-fat diets will increase satiety, so that you spontaneously eat less and loose weight. Diets high in refined carbohydrates like sugar and white floor will have the opposite effect. Even though moderate excercise seems to reduce appetite, exercising too hard and for too long, will have the opposite effect. Remember the saying about working up an appetite! The same will happen with restricing food intake too hard: you will loose weight in the beginning but eventually you only get hungrier, and hungrier, and hungrier.
So we have come to the main problem with the "diet and excercise"-mantra. It ignores hunger. It ignores the biological fact that your body does not like change. This is the well know phenomenom of homeostasis: a self-regulating process by which a biological system - like the human body - tries to maintain stability. Things like body temperature, blood acidity, and the level of blood glucose are strictly regulated to keep as stable as possible. The same happens with your weight. Body fatness levels for instance are controlled by the hormone leptin. The more fat you have the more leptin will be secreted. Leptin acts as a satiety hormone inducing people to stop eating. At the same time obesity decreases the sensitivity of the brain for the action of leptin. This disregulates the mechanism of homeostasis. Although leptin levels are high you keep on eating because your brain no longer recieves the signals of this hormone.
Likewise, when you try to get your body into a caloric deficit by eating less and or excercising more your body will fight back to maintain homeostasis. And it will fight back in spades! This has been born out by the experminents done by Ancel Keys with 36 concencious objectors soldiers during WW2. During this so-called Minnesota Starvation Experiment they were subjected to a semi-starvation diet. To be sure, they lost weight, in huge amounts even. But they also started obessing about food and went through a gruelling period: "many experienced anemia, fatigue, apathy, extreme weakness, irritability, neurological deficits, and lower extremity edema". A more recent version of this experiment can be seen with the biggest loser show. As Gary Taubes somewhat ironically comments:
Dieting doesn't cure obesity. That's not news, although it was reconfirmed last week in a particularly mediagenic fashion in a study published by National Institutes of Health researchers. The researchers followed contestants from the “The Biggest Loser” television show as these formerly obese contestants proceeded to regain most of the massive amounts of weight they had lost on the show.
As reported in the journal Obesity, these “Biggest Loser” contestants were the victims of “metabolic compensation.” As they tried to keep their weight under control, their bodies remained particularly resistant to expending energy. The findings implied that to maintain their weight loss they would have to remain hungry and calorie-deprived for the rest of their years, and they might still regain the weight they'd lost and then some. For anyone with weight to lose, the message was dismal.
The conclusion is simple: it's not just about establishling a caloric deficit. If that were the case we wouldn't have an obesity epidemic in the first place. The secret to weight loss - sustainable weight loss - is about creating a caloric deficit without increasing hunger. The secret fortunately is out there. We just have to move away from the barren dogma of eating less and moving more.