Fad Diets: How They Work, and How They Don’t

Let’s start from the very beginning. We have three main macronutrients (big nutrients) to fuel the body: Protein, Carbohydrate, and Fat. Nearly everything we eat contains all three of these, but some foods have more of one nutrient than the other two. Each macronutrient contains energy measured as calories. Protein and Carbohydrates each contribute 4 calories per gram. Fat contains 9 calories per gram. All three macronurtients (yes, including fat) are important for an energetic, healthy system. The body has special mechanisms to extract the energy from each of those sources, which we will go over in a later post. And while some people may be better at absorbing, processing, and utilizing the energy from certain fuel sources over other sources, we all basically have the same capacity (and necessity) to use all three fuels.

So let’s do some math.

Calories in – calories out = net energy balance

If we eat more than we burn, we have a positive energy balance, and if we burn more than we eat, we have a negative energy balance. In many cases, while maintaining weight, we want that energy balance to be zero. However, if you want to gain weight, you want a positive energy balance, and to lose weight, you’ll want a negative energy balance. Make sense? Great!

How do fad diets work?

Diet is a word that gets misused- a lot. We in the nutrition industry refer to your diet as anything that you’re eating. The weight loss industry uses “dieting” to refer to some type of restriction to your diet, or a specific set of rules that define your diet. So when I ask you what your diet’s like, I don’t expect you to be restricting anything, I just want to know what you’re eating.

So a fad diet is typically a set of rules or restrictions to what you can eat. You’ve heard of them – South beach, Atkins, Subway. (Can you think of any more?) Most fad diets will restrict a single macronutrient, typically cutting out most (if not all) carbohydrates or fats. They typically make one macronutrient out to be evil and avoided at all costs. Why all the hate for carbs? Why all the hate for fats? They’re both vitally important fuels! Lots of research through the 80’s and 90’s made a lot of assumptions on how those nutrients are metabolized by the body. They talk about how fats make you fat, and carbs turn into fat! Not the whole story, but we’ll get to that later.

Why do they work? What’s really happening?

Fad diets, while all claiming to be the best, essentially all work the same way – Calorie Restriction. Remember that math problem up there? In order to lose weight, we need to burn more calories than we consume. Well when you completely cut out certain foods from your diet, guess what, you also cut out calories. And, in general, if you cut out foods with excessive fat, and excessive carbohydrates, you will also cut out excessive calories. So yes, the fad diets work! Fewer calories, less fat, right? Well….we’ll get to that. But let’s break it down first. Let’s take that person who decided to cut out all the carbohydrates. No more pasta, no more buns. Was it the pasta making that person gain weight? Probably not. It was most likely the amount of pasta that did it, since we, as a culture, have no comprehension of serving size. And now we cut out a bun from our hamburger, so we no longer eat those calories that we would have had. Same thing, we’re eating less, so we’re consuming fewer calories, and therefore we lose weight. It’s all part of that math problem.

How do fad diets fail?

Do you know anyone who tried a fad diet and didn’t lose weight? If they did lose weight, could they keep it off? Let’s go back to that carbohydrate restriction up there. Does the diet still work if you add an extra patty of meat to that burger to replace that bun? Depends on how many calories that extra burger has, but my guess is no, it doesn’t work anymore. It’s not the bun (alone- we’ll talk about bread in a later post) that was making you gain weight. It was the excess of calories. So if you replace excessive calories with a different source of excessive calories, then you won’t get to where you want to be. So that’s it? Nope.

Let’s check the nutrient path. One of my biggest pet peeves is the fat-free this, sugar-free that, calorie free-such and such. While that equation up there is true for calories, it’s not the whole picture. You see, the calories that you eat are not quite the same as the calories that you absorb, store, or burn. Wait what? Yeah, so it gets more complicated when you delve into metabolism, but I’ll try to keep this part simple. Foods are essentially chemicals. You have chemicals that help your body work better, and you have chemicals that cause damage to your body. Some chemicals are called vitamins and minerals. You need these. They are vitally important for helping your body metabolize fuels, defend itself, even transport oxygen! Important, right? If you don’t get them, guess what, you can’t use your fuels properly. You might have limited the calories you’re consuming, but *gasp* you’re also limiting the number of calories your body has the capacity to burn. You’re also putting yourself at risk for malnutrition. No, not good. And no, taking a multivitamin and doing a fad diet doesn’t completely work either. We’ll get to that. So a lot of important stuff is dissolved in fats, and a lot of stuff that contains carbohydrates also contains lots of vitamins and minerals. In other words, we can’t get rid of fats completely, and we can’t get rid of carbs completely. At least not for very long. And anything we add to foods that are fake substitutes for fats or sugars – not good for the body. Any body hear of Olestra? Two words for you. Anal leakage. Also for another post. Put simply, you cut out a whole aspect of a balanced diet, you’re not helping yourself.

Finally part three. A balanced diet. Your body needs carbs, fats, and proteins. Each person may need them in a slightly different ratio, but we all need them all, at least a little bit. Many people who restrict carbs for too long or fats for too long end up gaining all the weight back after they start eating carbs or fats again. It wasn’t the carbs or fats that were the problem. It was the choices of foods that were and will be the problem. The key is to go back to that original equation. Reduce calories without depriving yourself. It’s a balancing act that we all need to figure out for ourselves, but it’s not impossible. It just takes a little work to start out, then it’s smooth sailing.

So before you decide to try a fad diet, think about what you’re doing to your body. If you feel lost or confused about how to do this, they’re coming up in future posts. Things that we’ll cover in the future:

  • Calorie restriction vs. Extreme Calorie Restriction
  • How fat is used in the body
  • How carbohydrates are used in the body
  • Healthy sources of fats
  • Healthy sources of carbohydrates
  • Vitamins and minerals – how the heck do they work?
  • much much more.
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