The biggest problem with your body transformation goals start—and end—with your diet. Yes, exercise is also extremely important. And even the best diet won’t offset a lack of physical activity.

If the engine is broken, it doesn’t matter what type of fuel you add to the machine.

But if the fuel is terrible, your body still won’t function the way you want.

Between fears of high protein diets, high fat diets, and really any type of carbohydrate, eating has become an overcomplicated mess that creates more stress than needed.

It’s time to change that mindset while simultaneously changing the way your body looks.

Use this guide to understand what your body needs, and why you don’t have to frustratingly avoid certain foods that you want as part of your healthy living plan.

Carbohydrates: The Misunderstood One

Carbohydrates seem to be the focus of most diets you read about (especially fat-loss diets), so it makes sense to start here.

Carbs have taken a real beating in the media ever since some guy named Atkins (you may have heard of him) decided we weren’t allowed to eat doughnuts anymore. (Prior to this we were allowed to eat doughnuts, but they had to be reduced fat; this made us feel better about ourselves.)

All joking aside, carbs have a bad reputation, or at least a worse one than they deserve.

Carbs come in a variety of forms. Some are good for you, and some are bad. The bad ones are usually highly processed and could barely be considered food other than the fact that they’re edible. They may be delicious, but they’re also the result of some crazy scientific processes.

Of course, if you process the crap out of anything, it reaches a point where it just isn’t healthy anymore. This doesn’t mean carbs are evil and to blame for the obesity epidemic—it just means that eating processed foods that are loaded with sugars and highly palatable are great at making people fat.

Why? Because we end up eating far too much of it. The reality is, your diet can include some processed carbs too, as long as it’s a minimal amount of the overall amount you eat.

Carbs 101: Simple vs. Complex

Carbohydrates are made up of sugar molecules, which your body breaks down into fuel, especially when you’re working hard. Sugars, starches, and fiber are all basic forms of the carbohydrate.

There are two main types of carbohydrates: simple and complex.

We could also mention fibrous carbs that you can find in foods like green veggies, lettuce, cabbage, broccoli, sprouts, spinach, cauliflower, peppers, cucumbers, zucchini … buuuut we won’t.

For the purposes of this discussion of carbs, we only want to touch on stuff that is probably causing issues with your weight. This doesn’t mean that these foods don’t count. They do.

But I don’t think a primary cause of weight gain is eating too many vegetables. And after coaching literally thousands of people, it’s become very clear that eating more veggies has always been a good thing.

Quite simply, eating vegetables allows you to eat more. And by eating more, you’re less hungry. And when you consider that hunger is strongly associated weight weight gain, winning war on hangry is half the battle.

Simple Carbohydrates

In the most basic sense, simple carbohydrates include table sugar, syrup, and soda. Most of the time, these carbs should be avoided (exceptions include cheat days or small daily indulgences, which should be included in any plan) and are usually the “bad carbs” that fitness pros talk about. Also included on this list are things like candy, cake, beer, and cookies. In other words, the best ones.

Complex Carbohydrates

Complex carbohydrates include oatmeal, apples, cardboard, and peas.

For a long time, people believed that complex carbohydrates were universally better for you than simple carbohydrates, but that isn’t always the case.

You see, your body takes both complex and simple carbohydrates and tries to break them down into useable sugar energy to fuel your muscles and organs. It’s not the type of carbohydrate that really matters, but how quickly your body can break it down and how much it will spike your blood glucose levels.

It’s not as simple as dividing complex carbs from simple ones, though. A slightly more sophisticated way to rate carbohydrate quality is something called the glycemic index (GI).

The GI attempts to classify foods by how quickly they break down and how high they boost blood sugar levels.

For a while, the GI was all the rage, and people argued that by following a low-GI diet, you’d keep insulin levels in check even while eating more carbs overall.

This has turned out to be only partially true. Which is to say that while it’s probably better to eat low GI foods than high ones, there probably won’t be a tremendous difference in your waistline if you’re still eating your weight in sweet potatoes instead of Cheerios.

Neither low-carb diets nor low-GI diets are a magic pill for fat loss; the main thing is to eat the right amount of healthy foods that fuel metabolism, which in turn will help you burn fat.

The important thing to remember is that your body needs carbs, even if some of the fad diets tell you otherwise. This becomes even more important if you’re performing intense exercise. Without carbohydrates, your body will begin to break down your muscle tissue to fuel your body, which will sabotage your efforts.

Carb lovers lament low-carb diets, and anti-carb crusaders posit that you can avoid carbs for the most part and still do well.

It is true that low-carb diets offer many health benefits, but as I’ve stated before, low carb doesn’t mean no carb.

Just as important, those health benefits don’t mean low carb is strategically better for fat loss. Research published in The American Journal of Clinical Nutrition dropped a bomb when it compared a lower carb diet to a higher carb diet and discovered no significant difference on fat loss, metabolism, or muscle retention.

Your Eating Tip: Ultimately, the number of carbs you eat is going to be highly based on personal preference, activity levels, and how your body reacts to what you eat. Carb intake should be determine after you prioritize fat and protein levels.

Fats: From Zero to Hero?

For a long time, fats were like carbs—blamed for every health problem possible. It’s the reason that for nearly twenty years, low fat was synonymous with healthy.

And for many people—maybe even several of you reading this—that’s still how you determine if something is safe to eat. If it’s low fat, it has to be good. Or if it doesn’t have saturated fat, then it’s okay.

Much like any silver bullet nutrition solution, this isn’t the case. As our nation’s fat consumption decreased, its obesity increased, according to CDC data. This was due to a variety of factors—the frequency of meals and snacks, the size of meals, and the consumption of sugar.

So what is the bottom line on fat? For starters, fat is a necessary component of your dietand something you’re probably not consuming enough of.

Fat is good. It’s good for testosterone. It’s good for your heart (yes, you read that correctly). And it’s good for your muscles.

Fat plays an important role in helping the general functioning of your body. Fat is a critical coating for nerves. This coating serves to speed up conduction down the nerve so that every neurochemical signal that is sent through your body (any time your brain wants to tell your body to do something), it happens efficiently.

What’s more, fat also serves as a substrate for a whole set of hormones known as eicosanoids. Eicosanoids are essential for numerous functions that regulate things like blood pressure, inflammation, and even blood clotting. This kind of fat is needed for basic human physiology, which is reason enough to include it in your diet.

Now that you know what fats are needed in your diet, here’s what you should know about the different types of fats—and why each needs to be included in your diet, with the exception of trans fats.

Monounsaturated Fat

Monounsaturated fats are found mostly in high-fat fruits such as avocados as well as nuts like pistachios, almonds, walnuts, and cashews. This type of fat can also be found in olive oil.

Monounsaturated fats help lower bad cholesterol and raise good cholesterol. They’ve also been shown to help fight weight gain and may even help reduce body fat levels.

Polyunsaturated Fat

Like monounsaturated fats, these good fats help fight bad cholesterol. Polyunsaturated fats stay liquid even in the cold because their melting point is lower than that of monounsaturated fats.

You can find polyunsaturated fats in foods like salmon, fish oil, sunflower oil, and seeds. Polyunsaturated fats contain omega-3 and omega-6 fatty acids, which have largely been processed out of our food.

Omega-3s and 6s are very important and are oftentimes referred to as essential fatty acids, or EFAs. These cannot be manufactured by our bodies, and so it becomes essential to ingest them. And because your body needs these sources to function optimally and remain healthy, it’s your job to make sure your diet has enough of these fats to avoid problems and breakdown.

Saturated Fat

Saturated fats might be the most misunderstood substance you can eat. And for good reason: there have been studies linking high intake of saturated fats to heart disease. But those studies also have more questions than the Riddler.

When researches have gone back in and looked at the data from all the countries where data was available, there actually was no link between fat consumption and heart disease deaths.

Much of the debate about dietary fat comes from sources like The China Study and movies like Forks Over Knives, which have pointed the finger at saturated fats—and all animal fats—as the reason for all health problems. And yet, these studies all took a very slanted bias toward the saturated fat hypothesis and completely ignored populations that were incredibly healthy despite diets based on saturated fats.

In fact, people who live in Tokelau (a territory off of New Zealand) eat a diet that is 50 percent saturated fats, and they have cardiovascular health superior to any other group of people, and yet this data and information is ignored.

There are several studies of hunter-gatherer tribes that consumed 50 to 70 percent of alltheir calories from saturated fats without any health problems. When you receive the specific calculations for your fat intake, up to half of the fat can derive from saturated fats.

Even Walter Willett, chairman of the Department of Nutrition at Harvard, has publicly stated (after a twenty-year review of research) that fats—and more specifically saturated fats—are not the cause of the obesity crisis and are not the cause of heart disease.

Listen, saturated fat is one of the best sources of energy for your body. It’s why your body naturally stores carbohydrates as saturated fat.

Are you going to argue with one of the most basic structures of how your body was intended to work? Not to mention, saturated fats are some of the most satiating foods, meaning they keep you fuller longer.

And research shows diets that are higher in saturated fats are oftentimes lower in total calories consumed.

That leaves you with one option: assuming you’re not a vegetarian, you should be eating red meat, dairy, and eggs to consume your share of saturated fats. Not overeating them, or downing sticks of butter like they’re going out of style. But also not avoiding them as if they’ll break the scale.

The exception: Trans Fat

Trans fats are the black sheep of the fat family. Trans fats are the worst fats, and in truth, one of the worst forms of food that you could possibly consume. They’re found in foods such as French fries, potato chips, and most fried foods.

While some trace amounts of trans fats are naturally occurring in meats and other foods, by and large, most are not naturally occurring. Instead, they are generally manmade.

Trans fats are made by a chemical process called partial hydrogenation.

Manufacturers take liquid vegetable oil (an otherwise decent monounsaturated fat) and pack it with hydrogen atoms, which convert it into a solid fat. This makes what seems to be an ideal fat for the food industry because it has a high melting point and a smooth texture, and it can be reused in deep-fat frying.

Essentially, trans fats come about as a result of overprocessing our foods in order to offer consumers a longer shelf life. If your food is pre-packaged, it’s a pretty safe bet that it has its fair share of trans fats. If you are serious about your goals, you should try to avoid trans fats at all costs. Or if you just don’t want to be eating plastic garbage.

Of course, we take a moderate approach. If you’re limiting your intake of junk foods, exercising regularly, and getting good nutrition otherwise—including a variety of healthy fats—then chances are, you can have the occasional Twinkie once every few months and be okay.

Your Eating Tip: Research suggests that about 20 to 35 percent of your daily calories should come from fats.

Protein: The White Knight

While both carbs and fats have spent their time as public enemy #1, being demonized or lauded by turns, no macronutrient has enjoyed the rise to prominence and popularity as our friend, protein.

A favorite among bodybuilders, athletes, and just about any fitness enthusiast, protein is used by your body to repair damaged muscle, bone, skin, teeth, and hair, among other things. Think of it as the mortar between the bricks; without it, the entire structure of your body begins to break down.

Unlike other nutrients, your body can not assemble protein by combining other nutrients, so it needs to be prioritized if you’re to achieve your healthiest (and best looking) body possible.

Protein helps to create an anabolic hormonal environment (good for muscle building and fat loss), and along the lines of the brick metaphor, it provides a lot of the materials used to build your muscles.

There are two categories of protein: complete and incomplete.

Protein is comprised of smaller molecules called amino acids. There are twenty-two amino acids that warrant attention, of which nine belong to a subcategory that can only be obtained through your food. Your body can manufacture the remainder of the amino acids.

The nine amino acids that are obtained from food are called essential amino acids. For those interested in such things, the essential amino acids are:

• Tryptophan
• Lysine
• Methionine
• Phenylalanine
• Threonin
• Valine
• Leucine
• Histidine
• Isoleucine

A complete protein (also known as a whole protein) is one that contains adequate portions of those nine amino acids. By contrast, an incomplete protein is one that is lacking in one or more of those amino acids.

These amino acids also help your body create hormones that help regulate things like blood pressure and blood sugar levels, which are directly responsible for your metabolic rate and muscular growth. In short, protein is extremely important, especially the complete proteins that are found in foods such as fish, poultry, eggs, red meat, and cheese.

The Pink Elephant: The Kidney Question 

Some “experts” would like to have you believe that eating lots of protein will cause all sorts of problems, ranging from kidney stones and gallstones.

For most people, this is not a concern—or rather, it is a moot point. That’s because there’s no research showing any relationship between eating lots of protein and developing kidney problems.

In fact, a study in the Journal of Strength and Conditioning Research tested up to 400 grams of protein per day without any negative consequences. Now, if you have a preexisting kidney problem, it’s possible that a higher protein diet could be hard on your body. But if you have a kidney problem, you should be talking to your doctor about your diet anyway.

If you’re healthy, you are clear to eat protein and not worry about any health problems—because there are none.

What’s more, protein is one of the most metabolic macronutrients, meaning that the more protein you eat the more calories you burn. For that reason–and protein’s ability to help spare muscle mass–it’s a common reason why if you’re going to overeat on any macronutrient, protein is usually your safest bet.

But don’t forget—calories are still calories so you can’t eat as much as you want.

Your Eating Tip: Protein should be set about .5 to 1 gram per body of goal body weight. If you’re very active, you can veer slightly upward, but it’s not necessary and should be based more on food preference than anything else.