Yes, every possible diet you can think of works. Some work better, others are what we call “crash” diets. They make you lose a significant amount of weight fast, usually by starving you.

In 1963, a group of researchers in the Institute for Metabolic Research from Oakland, California set out to study the effects of varying diet compositions on weight loss when calories were controlled. The caloric intake was consistent, but the composition of the diet was changed at different intervals.

For example, the fat intake varied from 12 to 83 percent, protein changed from 14 to 36 percent, and carbs from 3 to 64 percent.

During each revision of the diet, weight loss stayed consistent. The researchers concluded that caloric intake is the most significant factor for weight loss, regardless of diet composition. The study’s name? Calories do count.

A similar study from recent times ended up with the same conclusion:

"Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize."

And finally, this review came to the same conclusion:

"We conclude that a calorie is a calorie. From a purely thermodynamic point of view, this is clear because the human body or, indeed, any living organism cannot create or destroy energy but can only convert energy from one form to another."

A calorie is a calorie, regardless of macronutrient composition. That is why there are so many “effective” diets out there.

The low carb diet makes you restrict your caloric intake thanks to the reduction in carbs. The ketogenic diet makes you restrict calories even further by completely eliminating carbs. You can only eat so much protein before you’re stuffed. Vegan diets also reduce your caloric intake by making you eat low-calorie foods all day.

So, all diets that make you cut out a macronutrient or food group make you eat fewer calories and thus lose weight. The problem is not in the weight loss. It’s in the weight loss maintenance. In other words, sustainability.

You see, most, if not all diets are super restrictive. To the point where you start going insane. You follow it, you get the results, and then...

You’re off the diet. What happens then is the turning point for most people:

They start eating the way they used to eat before and gain all the weight back, and then some. Let me give you an example to illustrate my point:

You’re an average dude, and you need about 2500 calories/day to maintain your current weight. One day, you decide to start the Ketogenic Diet, cut out all carbs, and start eating meats, cottage cheese, milk, eggs, leafy greens, etc. Without even knowing it, you’re now eating no more than 1600-1700 calories/day because it is hard to eat more with that diet composition.

Of course, you start losing weight. You instantly lose 5-7 pounds thanks to glycogen and water depletion and think to yourself “Whoa, this is the best thing ever!” Life is good. You’re losing weight at a fast rate, and you eventually get to your goal. But then, the diet ends, and you start eating as usual. You reintroduce carbs and your caloric intake returns back to normal.

Except...

The new caloric needs are lower than they were before your weight loss. Thanks to the natural metabolic adaptation and the lower body weight, your new maintenance calories aren’t 2500/day, but more like 2100.

And when you couple that fact with the cravings that you’re feeling at the end of a diet, you can see where things take the wrong turn. Because of your elevated hunger levels, you can be eating upwards of 3000 calories per day and gaining back the weight fast.

So what’s the bottom line?

You starved yourself, lost a bunch of weight, started eating more, and gained back everything. The widespread “yo-yo effect.”

If you’re interested to know what makes a diet effective, practical, and enjoyable, click here to read the post I wrote on the topic.

Until next week,

Philip

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