There's a lot of confusing messaging when it comes to health, nutrition, and weight loss. Imagine my surprise when I read several foods listed under the headline "30 Foods to Eat After Age 30" 10 Foods to Boost Libido. "As a thirtysomething woman, I really wondered if the wellness industry was trying to tell me something.

(Whatever it is, you can tell it to my medicine cabinet full of anti-aging skin care products 46 sex toys. Yes, I have a literal armoire.)

With all the conflicting information floating around the Internet, it’s no wonder we have so much confusion about what we should eat, how much of it, and how to stay healthy—and why we're convinced that some foods are good, some are bad, and some you absolutely shouldn’t eat.

The easy answer is that you should not eat raw chicken, anything that you have a diagnosed allergy to, and any overpriced magical brew claiming it will "detox" you. Other than that, if you want to know how and what to eat for health, you can learn about the basics and figure out from there what works for you.

Let's start with a fundamental question: What is a calorie?

In the scientific sense, a calorie is the unit of energy needed to raise 1 gram of water 1 degree Celsius. When you think of calories, think of them like that: as energy. The stuff that keeps you going. Do not overfill your tank and flood the engine, but you're going to have a lot of problems trying to run on empty.

Calories come from three main macronutrients: protein, carbohydrates, and fats. Everything you eat is some combination of macronutrients (except maybe mushrooms ... and whatever Gwyneth Paltrow lives on). They all have uses in the body in the appropriate amounts, even cholesterol, which is a type of fat, and sugar, which is a carbohydrate. Each macronutrient can be used as an energy source, and technically each produces the same unit of energy per calorie. That being said ...

It's a drastic oversimplification to say "a calorie is a calorie."

The macronutrients all have very different chemical structures and complex sets of jobs in your body. Let's take a look at each one.

At 4 calories per gram, we generally think of carbohydrates mainly as a source of energy, and that's pretty accurate. They've gotten a bad rep in the last few decades or so, but your brain lives on sugar. Remember eating Cocoa Pebbles before big exams? Fine, maybe that was just me, but it actually was based on sound science. If you’re active, carbs are a great source of energy. The "problem" with carbs, which isn't actually a problem, but rather just a question of math, is that when you're not active, or you eat way more simple carbohydrates than your body can use for energy, it gets stored as fat. And the truth is, yeah, a lot of us eat a lot more carbs than our bodies need.

You also may have read recently that sugar is as addictive as cocaine, which sounds bad, but actually isn't the case. While the lure of sugar can be strong for some people, current science just doesn’t seem to support that headline-friendly notion. Really, when was the last time someone sold their possessions for a cronut? A 2014 study from the University of Edinburgh found that people could show addiction-type patterns around eating, but that did not addictive behavior. So enjoy carbohydrates in the right amount for your activity level.

Fat has multiple uses in the body. It's used in cell wall repair, hormone regulation, and storage of fat-soluble vitamins. An extreme lowfat diet can impede any one of these. The reason why fat gets a bad reputation is that it packs 9 calories per gram, and a lot of high-fat foods are not extremely nutrient-dense. You do not need to be scared of bacon (because bacon), but moderation is the key to fatty foods in the food industry. / 78

And speaking of bacon, let’s talk protein, that thing we're never quite sure if we're getting enough of it. Protein is responsible for a lot of the needs of your body. Like carbohydrates, protein has 4 calories per gram. But unlike carbs, and the vast advantage of protein is that it's the best macronutrient for satiety, according to a meta-analysis from a 2016 study from Purdue University. A lot of people worry about getting enough protein, but all reports show that you're getting plenty of it just by eating a varied diet. Do not be dragged in by the labels that say "added protein" unless you're trying to grow biceps on your biceps.

Does your body turn sugar into fat?

Yes, but your body can also convert protein and fat into sugar. When needed, there are pathways for each calorie to be converted to a usable form of fuel. Conversely, every calorie can be converted and stored as if you have an excess of calories in your system. Busting a related myth, you do not "convert fat into muscle" when you lose weight. You can lose weight and gain muscle at the same time giving the impression that it happens, but fat deposits can not be converted directly into muscles.

What’s considered a good source of calories?

It really depends on your caloric needs , but in general terms, foods that we consider healthy, tend to have a high ratio of micronutrients (ie, vitamins and minerals) per calorie. Vegetables, lean meats, fruits, berries, whole grains, and lentils are all the examples of foods that easily meet this criteria.

Some foods are calorically dense without providing a lot of micronutrients, and that does not make them bad or off-limits.

There's no morality with food or calories. The food simply is, and it's up to you to make intelligent choices with the food and your health ... and once in a while, with your taste buds, because godammit, cronuts exist. Moderation, but get the veggies first!

Is it easier to maintain a healthy weight on certain foods or a certain diet?

A lot of that comes down to personal preference. Nobody is great at tracking calories -not even registered dietitians-because we all tend to incorrectly estimate our intake. So how do we manage this? Find what works for you. Long term, there's no advantage to a low-carb diet versus a lowfat diet for weight loss, because both work the same way: by inducing a caloric deficit. For every story like Supersize Me, there's a guy who loses 56 pounds eating nothing but McDonald's while meticulously counting calories. Every diet plan will work if you stick to it because, no matter what, diets work by inducing a caloric deficit. Truly, the best diet plan is one that you can stick to. (Not that sticking to a diet is an easy feat—it isn't, and dieting can be a complicated journey. But that's another story.)

It's not magic, it's just science.

Fruits and vegetables are mainly carbohydrate, fiber, and water. Lentils are protein and carbs. Meats are protein and fat. And processed foods, well, read the labels and find out. But there's nothing intrinsically wrong with any of them. They're all just combinations of calories. If you want to enjoy something that's a dense source of calories, enjoy it. If you're trying to lose or maintain your weight, just keep track of it. And never let an online list tell you that there are calories-or anything-that you're too old to enjoy.

Yvette d'Entremont holds a B.S. in chemistry, B.A. in theatre, and a master's degree in forensic science with a concentration in biological criminalistics. She worked for eight years as an analytical chemist before her blog focused on debunking bad science,, turned into a full-time job in science communications. Follow her on Twitter and Facebook.

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