From low-carb to ketogenic to vegan, diets sold on the promise of weight loss pop up every year. Some, like the Atkins diet, become hugely popular. The whole range of weight loss diets are a dizzying array. But so many pop up that people may start to wonder. If this diet really promises weight loss, how come it’ll inevitably be unknown in a few years? And it’s true: from macrobiotics to juice diets to cabbage diets, there’s plenty of once-lauded weight loss plans that have been cosigned to the graveyard. So what makes a diet work? If you want to lose weight, what’s the best option?

The answer to that question is both simple and complex. The key to weight loss is simple: burn more calories than expended. To lose a pound, take in a total of 3,500 calories fewer than expended. Seems simple, right? It is. So why is it also complicated?

For one, this approach requires calorie counting. Most people, even those who are determined to lose weight, don’t know how many calories are in something. Even if they do, they underestimate how much they eat at a serving. Or they don’t realize the calories they need to consume for real weight loss. And calorie counting requires counting everything eaten. Lots of people engage in mindless snacking.

The very fact calorie counting is so exacting is probably what makes fad diets that promise instant weight loss so popular. Whether it’s the low-carb, high fat diet, or the raw vegan diet, many diets promise weight loss without the business of calorie counting. However, that is what will ultimately cause weight loss. Whether you eat only potatoes, McDonald’s, or Twinkies, if it’s less than you burn in a day, you lose weight.

However, a diet made of only Twinkies or McDonald’s isn’t going to be very easy to maintain over the long term. A diet shouldn’t be thought of as a ticket to weight loss with an end in sight, but a total life change. Part of the challenge is not feeling hungry with a reduced calorie count, and it is there where the vegan, ketogenic, and low-carb diets can be useful. None are the key to magic weight loss, but if one of them combined with calorie counting helps keep the person full without the extra calories, it’s a help for that one person. And if that diet helps keep the weight off, it’s working.

Weight loss isn’t about going on a diet; it’s about learning to not eat excessively. So pick the one that helps you feel full, gives you all your needed nutrients and gives you energy, no matter what it is. Just don’t assume your weight loss diet isn’t about the calories and make the terrible decision not to count them.

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