Protein, Carbs, and Fat: The Importance of Macronutrients for Weight Loss

While we have all heard the expression, “Calories in, calories out!” as a method for preventing weight gain, it should come as no surprise that not all calories are created equal. It is true that if you burn more calories than you consume, you will lose weight.  However, that is certainly not the entire picture when it comes to weight loss. A more in-depth look at your diet will reveal the types of calories that you are taking in when you eat. Macronutrients, or “macros” for short, refers to the categories of molecules in the food you eat: protein, carbohydrates, and fat. This blog post will examine each and help you to make sense of how monitoring your macronutrient intake can help you lose weight.

What are Proteins?

Proteins are molecules that are made up of long chains of amino acids. There are 20 different amino acids in human proteins, and the type and function of each protein are determined by the identity of the amino acids in the chain.  We generally think of proteins as the major component of your muscles.  That is certainly the case, but proteins do much more than make muscle! Every one of your cells must carry out specific functions, and the molecules that do the work in each of your cells are proteins. For instance, there is a series of steps that allow your cells to break down glucose, or sugar.  Each of those steps requires a protein, called an enzyme, to help the chemical reaction proceed. Proteins are also involved in sending messages from cell to cell. Insulin, for instance, is a protein hormone that causes many changes in your cells when it is released.

Per gram, protein contains 4 calories – meaning if your protein shake has 20 grams of protein and 150 calories, 80 of those calories are solely from protein. Throughout the course of a day, patients should aim to consume at least 60 grams of protein. Besides protein shakes, other sources of protein include fish, beef, poultry, pork, beans and legumes, dairy, eggs, nuts and seeds, whole grains such as quinoa. Fruits and vegetables contain minimal protein, however they are very rich in vitamins and minerals.

What are Carbohydrates (or Carbs)?

Carbohydrates are sugars. Each carbohydrate is made up of a chain of single sugars.  Examples of sugars that might be familiar are glucose, lactose, and fructose.  “Simple” carbohydrates are fast and easy for your body to break down and quickly raise your blood sugar.  “Complex” carbohydrates, in contrast, are made up of several different types of sugars connected in different ways; they take more time for your body to break down and do not raise your blood sugar as quickly. It is important to distinguish between the two when you are choosing foods, as the consumption of high quantities of simple carbohydrates creates spikes in the body’s production of insulin, which has been connected to weight gain. While some carbohydrates are to be avoided, your body uses sugars for many things, such as building DNA and cell signaling, among others.

Per gram, carbohydrates contain 4 calories – meaning if your protein shake has 10 grams of carbs and 150 calories, 40 of those calories are solely from carbohydrates. Initially after surgery, patients may eat as little as 30 grams of carbs per day, since the focus is protein. As time goes, this may increase to greater that 100 grams by incorporating more fruits, whole grains, and healthy starchy vegetables.

Carbohydrates get a bad reputation, however your body needs some carbs to survive. Examples of carbohydrates to AVOID include white breads, rice, pasta, desserts, sugar-sweetened beverages, juice, cereal, heavily sweetened yogurts, and pastries. Carbohydrates to gradually incorporate in your diet include whole grains such as quinoa, farro, and oats in addition to whole fruits, legumes, and potatoes.

What are Fats?

Fats are unlike carbohydrates and proteins in that they are long chains in themselves, generally not made up of a chain of smaller units. The body uses fats for energy storage, as they can be broken down bit by bit to release a great deal of energy. Fats are also important for the proper functioning of the nervous system, the structure of cellular membranes, and they serve as the molecular basis for some of the body’s important hormones.

Per gram, fats contain a whopping 9 calories. This is why we want to limit fat, as these calories add up quickly! With that being said, you cannot eliminate fat completely because fats are extremely important as stated above. Each meal should contain less than 10 grams of fat.

Similar to carbohydrates, there and healthy and not-so-healthy sources of fat. Examples of fats to AVOID are the kind that can attribute to high cholesterol, clogged arteries, and heart disease such as fatty cuts of beef, lamb, bacon, poultry with skin, fried foods, lard, cream, butter, whole fat dairy products, and whole fat cheese. Fats to incorporate into your diet, in moderation, include avocado, fatty fish, low-fat dairy products, nuts, lean cuts of beef, poultry without skin, eggs, and olive oil.

So how can “Macros” Contribute to Weight Loss?

While counting calories may give you an overall picture of your energy intake and expenditure, counting “macros” can help you to get an idea of the quality of your diet.  The calorie count on two cupcakes may be similar to the calorie count on a half breast of baked chicken, a cup of broccoli, and some sweet potato fries, but the macronutrient breakdown is vastly different. Interestingly, while the two “meals” may have the same calorie count, one promotes weight loss, and the other promotes fat storage.  This is because high-carbohydrate meals trigger fat storage and hunger cravings, while meals that are rich in protein, healthy fats, and complex carbohydrates cause the body to feel satiated for longer and provides your body with the critical building blocks it needs. It is no secret which is the better choice of the two options.  Having targets for your daily consumption of protein, carbohydrate, and fat intake can help you to make healthier choices for weight loss. Weight-loss plans can account for target intake of the macronutrients.  Whether accompanied by bariatric surgery or as a dietary option alone, it is a good idea to consider the “macro” makeup of your meals. Also, while it is important to consider the macronutrient profile of your food, micronutrients (vitamins and minerals) are also critical (Kim et al. 2018); those foods that have healthier macronutrient profiles are also often likely to be more nutritionally dense and can better contribute to your well-being.


Kim et al. (2018). Reuniting Overnutrition and Undernutrition, Macronutrients and Micronutrients. Diabetes/Metabolism Research and Reviews. e3072.