Keto. Atkins. Vegan. Vegetarian. Paleo. Carnivore. Pescatarian. Macros.
If you know any of those above words, then you know of the diet fads out there and have some clue of how many different ways to eat there are out in the world. Often, the question we get is, “What diet should I do?” And the truth is simpler than most think it may be: it doesn’t matter.
All of the above diet fads work for losing fat or leaning out. They all work so well that people have created entire diet identities (a term coined by Dr. Jordan Shallow) about how they eat. “I’m vegan,” “I’m keto,” “I’m Paleo,” and so on. But we’re all human, and to understand why each of the above diets work we have to understand how we lose fat, gain muscle, and reclaim our overall health.
The biggest determining factor in any diet protocol is the balance of calories in and calories out.
It comes down to energy balance. Whatever you burn in a day is what you need to eat to maintain a consistent weight, and if you go over that consistently you will gain mass, or lose mass if consistently under it. For most individuals that is all that matters. Calories in equaling calories out.
Each of the originally listed diet fads work for weight loss due to the restriction of what you can eat, ultimately leading to a restriction of total caloric intake. Keto restricts carbohydrate intake, causing you to eat more satiating foods and ultimately eating less. "Going vegan" takes many higher fat foods off the menu, and leads to replacing fat with carbohydrates, which are less calorie dense and ultimately lead to a reduction in overall calorie intake. The list goes on and on.
Now, to understand these things, it should be said that whatever health or performance goal you have will also come with some nuance. The human gut microbiome (the fancy name for the digestive system) is marvelously complex, and is highly varied based on an individual’s genetic makeup. This is why when you try to start a new diet plan you should consult your physician and a Registered Dietician (not a nutritionist or personal trainer), because they have a deeper understanding of your individual health history.
It should also be noted that diets and performance do not always go hand in hand. Diets are usually calorie restriction based and not performance based. This means that it more aptly puts you in a position to lose fat or mass, which can be detrimental for some sports like football, field events, and other power sports. This again makes the situation more complicated, as the demands of the sport will create the necessary nutrition protocols for an athlete or individual seeking to perform optimally. (Also note the word change from diet to nutrition in that last sentence, as nutrition is more of a long-term eating strategy instead of a short-term goal achievement plan like a diet is).
This is where we must understand the original principle of calories in, calories out. Because it stands to reason that regardless of the goal being weight loss, muscle gain, or overall performance the principle will not change.