For years, the nutrition science establishment has repeated the mantra that a “calorie is a calorie.” What they mean by this is that it doesn’t matter what food you eat to get energy; it is all the same. So if you eat 2,000 calories worth of donuts or 2,000 calories worth of broccoli, the overall effect on your weight won’t change.
This unshakable faith, however, doesn’t come from nutrition science – it comes from physics. The first law of thermodynamics states that energy can neither be created nor destroyed. So if you put a calorie of food into your body, the thinking goes, you either have to burn it or store it as fat. There are no alternatives.
Of course, that isn’t actually how the body works.
Take nuts, for instance. Nuts are highly calorific food – around 600 calories per 100g – more than most junk food. This food group, however, doesn’t lead to weight gain. In fact, regular consumers of nuts tend to have lower waist circumference AND lower overall body weight. 
It begs the question, therefore, what the heck is going on? Why do people who sprinkle almonds on their porridge seem to weigh less if a calorie is a calorie?
Part of the explanation has to do with absorption. When you drink soda, practically all of the energy-abundant sugar in the drink passes into your bloodstream and becomes available for energy. But when you consume nuts, a lot of the energy never even gets into your body. Either bacteria in your gut feast on it, or it comes out in your poop.
Some foods, nuts included, also boost your basal metabolic rate – the amount of energy your body burns at rest. If you put somebody on a strict diet for six months, for instance, they’ll lose both fat and muscle, and so their resting energy consumption will fall. But if you feed them a bunch of spicy food, their basal metabolic rate will rise, allowing them to lose even more weight.
Many brands are cottoning onto this idea. They know that certain ingredients in foods are better for helping people lose weight than others. Cutting the cost of a diet using a Nutrisystem promo code could, therefore, also assist with weight loss. The body isn’t a simple machine, like a steam engine. Instead, it operates in complicated ways when it derives energy from food. Similarly, food itself is complex. Laboratory experiments might be able to calculate a specific calorific value from food, but that doesn’t mean all that energy is available to the human gut.
Physics, therefore, doesn’t provide all the answers in nutrition science. If you’re looking to get fit, build muscle, and lose fat, you need to pay attention to the constituents of food. Certain phytonutrients affect our biological processes at a fundamental level, changing us from the inside out.
Foods make people lose weight by changing their underlying metabolism in some way. Beans, berries, greens, nuts, herbs, and spices are all beneficial in this regard.
