There's a lot of confusing messaging when it comes to health, nutrition, and weight loss . Imagine my surprise when I read that several foods listed under the headline 30 Foods Never to Eat After Age 30 were also in a story called 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 antiaging skin-care products and my armoire of sex toys . Yes, I have a literal armoire. Who needs a list of libido boosters anyway?)

With all the conflicting information floating around the Internet, its no wonder we have so much confusion about what we should eat, how much of it, and how to stay healthyand why we're convinced that some foods are good, some are bad, and some you absolutely shouldnt eat.

The easy answer is that you shouldnt 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.

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. Dont overfill your tank and flood the engine, but youre 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 mushroomsand whatever Gwyneth Paltrow lives on). They all have uses in the body in 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

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 thats pretty accurate. Theyve 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 youre 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 doesnt 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 sugar and fat themselves did not promote addictive behavior. So enjoy carbohydrates in the right amount for your activity level.

Fat has multiple uses in the body. Its 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 dont need to be scared of bacon (because bacon), but moderation is key when it comes to keeping your caloric intake from fatty foods in line with what your body needs for fuel.

And speaking of bacon, lets talk protein, that thing were never quite sure if were getting enough of but are strangely lured in by if we see the number of grams of it on a label. Protein is responsible for a lot of the little repairs your body needs done on a daily basis and, of course, building muscle. Like carbohydrates, protein has 4 calories per gram. But unlike carbs, a huge advantage of protein is that its 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 youre getting plenty of it just by eating a varied diet. Dont be dragged in by the labels that say added protein unless youre trying to grow biceps on your biceps.

Yes , but your body can also convert protein and fat into sugar. When needed, there are pathways for each calorie source to be converted to a usable form of fuel. Conversely, every calorie source can be converted and stored as fat 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 fat and gain muscle simultaneously giving the impression that this happens, but fat deposits cannot be converted directly into muscles.

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

Theres no morality with food or calories. The food simply is, and its 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!

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, theres 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 , theres 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 featit isn't, and dieting can be a complicated journey. But that's another story.)

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 theres nothing intrinsically wrong with any of them, not even candy. Theyre all just combinations of calories. If you want to enjoy something thats a dense source of calories, enjoy it. If youre trying to lose or maintain your weight, just keep track of it. And never let an online list tell you that there are caloriesor anythingthat youre too old to enjoy.

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

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Are All Calories the Same? - SELF