It’s Time to Stop Worrying About Carbs, Fat and Protein.

Fad Diets Aren’t Bringing Us Any Closer to Health.

As I scrubbed my hands before starting an abdominal hernia repair, the attending asked, “How do you want to do this?”

“Not sure,” I confessed. “There are so many different approaches.”

He nodded. “You’ll hear surgeons defend one or the other, but don’t get caught up in that. Just tie strong knots.”

I’ve found that the advice speaks to more than hernia repairs.

In nutrition, we’ve been arguing for decades about the relative merits of carbs, fat and protein. But it’s a distraction that’s kept us from maximizing the nutrients most important to our health.

Let’s start from the beginning. Carbohydrates, fat and protein are collectively referred to as macronutrients. All three are made of long chains with repeating units.

  • Carbohydrates are made up of sugars.
  • Fats are (mostly) made up of fatty acids.
  • Proteins are made up of amino acids.

These repeating units serve a common purpose: fuel. And we measure the energy they give us in calories.

Carbs, fat, and protein also have separate roles that support our health.

Carbs provide quick, reliable energy in the form of glucose. Our bodies run on glucose and some tissues, like our brain and red blood cells, depend on it.

Fats pack their calories into a tiny space for easy storage. Fats also help with vitamin absorption, hormone production, and nerve function.

Protein offers amino acids to build everything from enzymes and antibodies, to hair and bone.

Though our body makes constant use of carbohydrates, fat, and protein, we don’t need to eat all three with every meal. Our body keeps plenty of reserves.

Glucose is saved as glycogen. Fatty acids are stored in body fat. And amino acids are available from muscle.

This supply of energy can keep us going for weeks without food, since carbs, fat and protein can all be converted into ATP. They can also drive countless other metabolic reactions necessary for things like to synthesizing DNA or tamping down oxidative damage. Macronutrients are like cash, checks and a credit card: they offer different ways of buying whatever you need.

Only a small amount of omega-3 and omega-6 fatty acids, as well as a certain group of amino acids, must come from directly from the food we eat.

So to a large degree, our bodies can run on whatever we fuel we choose.

But that still leaves us with the question, “What should we be eating?”

If you’re like many of my patients, you may just be interested in the easiest way to shed some pounds. It’s certainly a worthwhile goal. Losing that weight can brighten our mood and increase our energy. It also protects us in the long-term from diseases at the root of so much American disability and death; everything from joint pain to heart attacks and cancer.

Unfortunately, a lot of trouble can start during our efforts to lose weight. Diet schemes try to convince us that health is all about macronutrients. They encourage us to focus all of our attention on carbs, fat and protein. The Atkins Diet urges high protein intake and carb-restriction, while juice fasting pushes us to get almost all of our calories from carbs. The Zone diet strikes a middle ground by extolling meals with a balance of 40% carbs, 30% fat and 30% protein.

Fad diets offer plenty of justifications for the oversized attention they give macronutrients. Some diets say that their preferred macronutrient makes weight loss easy because it’s more “filling” than the others. This conveniently stretches the truth. Sure, fiber and protein-rich foods are more satisfying than the highly-processed junk. But beyond that, it’s hard to predict what type of foods will fill us up. One well-regarded study found that oranges are more filling than steak on a per calorie basis. It also demonstrated that cheese is more satisfying than lentils, and popcorn more filling than eggs.

Often the diets will claim that the “correct” macronutrient profile helps with speedy weight loss by altering your metabolic rate. And this definitely sounds appealing. But studies rarely detect any metabolic advantage in limiting a specific macronutrient.

We can’t escape the fundamentals of nutrition — weight loss happens when we expend more calories than we consume. This is true regardless of what you eat, as demonstrated by a nutrition professor who lost 27 lbs. in two months by eating a “convenience-store” diet of Twinkies, Doritos and Oreos.

At best, high-protein diets and extreme carbohydrate restriction may help us burn a little extra fat, equaling ~100 calories per day. But this doesn’t come close to justifying the sacrifice of some of our healthiest foods.

Sure, diets sometimes work. But the real question is how long does it last? With fad diets, the biggest challenge isn’t losing the weight, it’s keeping the weight off.

What diet gurus seldom mention is that as you lose more and more weight, your body uses less and less energy. This has a heartbreaking implication. It means that whatever you do to reach a new weight is what you need to continue doing if you want to stay at that weight.

Put another way: If the diet isn’t something you can do forever, then the change won’t last.

It’s no wonder long-term studies find that, regardless of whether a diet is high in carbs, fat or protein, the closer you stick to it, the better the results. The change has to be sustainable for the weight loss to last.

That’s exactly why we need to demand more from a diet than dropping pounds fast. The way we eat should align with our enduring aspirations. Our food choices should aim to bring us health and vigor. The weight will come off, and stay off, when we commit to eating right.

Arbitrary limits on carbs, fat, or protein, on the other hand, won’t get us there. The impact of food on our wellbeing is a complex calculus; it can’t be reduced to arithmetic.

For instance, both sweet potatoes and brownies are carbohydrate-rich, but only the sweet potato is healthy. Avocado and salami are both high in fat, though only the avocado does a body good.

Even when we break food down into saturated and polyunsaturated fats, or simple and complex carbs, we’re still oversimplifying how it affects our health.

Fortunately, there’s a lot more to nutrition than carbs, fat and protein. And it’s well worth talking about. Fiber, vitamins, minerals and phytochemicals all offer us exceptional benefits. In fact, it’s these nutrients that have an outsized influence on how food contributes to our wellbeing.

So don’t get caught up with the crazes around carbs, fat or protein. All the macronutrient tug-of-war is missing the point. Whether you want to lose 10 lbs. or live till you’re 100, the real answer is nutrient-rich foods. The next few articles will focus on what to be looking for!


1. Carbs, fat, and protein share a common purpose- they provide our body with energy.

2. Macronutrient intake doesn’t decide health. It’s all the other nutrients we get from food that play the biggest roles!

Thanks so much for reading! If you missed my introduction to the Nutrient-Rich Life series, you can catch it here. You can also check out the 3rd article that explains why fiber is a friend we all need. And be sure to follow me so you don’t miss the next one!