Basics of Low-Fat, High-Protein Diets

Karen Frazier
Reviewed by Terri Forehand RN
fruits and vegetables

Some people seeking to lose weight find they do well on a low-fat, high protein diet. Such diets are not for everyone, however, so it is important to understand exactly who can benefit from such a diet and who should avoid it.

Definition

Carbohydrates, fats, and proteins are all macronutrients your body needs for good health. A high-protein diet is one that contains a high percentage of plant and animal-based protein foods. High-protein diets naturally restrict carbohydrates, so you will often see the term "high-protein diet" used synonymously with low-carbohydrate diets.

While recommendations vary, the United States Department of Agriculture Food Plate recommends you eat between 10 and 20 percent of your calories from protein, no more than 30 percent from fat, and the rest from carbohydrates. A high-protein diet may recommend protein levels ranging from anywhere between 30 percent (in Barry Sears' Zone Diet) to 70 percent or greater.

Low-fat diets recommend eating fewer than 30 percent of your calories from fat, with some as low as 10 percent.

Efficacy

High-protein, low-fat diets are increasingly shown to be effective for weight loss.

  • A 2008 study showed high-protein, low-fat diets can be successful at reducing weight and improving body composition with even modest changes in macronutrient profiles by slightly reducing fat and carbohydrates and slightly increasing protein intake.
  • Another study showed that high-protein, low-fat diets were effective for weight loss and healthy blood lipid profiles.

Two Schools of Thought

Low-fat, high-protein diets work in two ways - by controlling insulin and restricting calories. This type of diet serves as a compromise between two very different schools of thought in the diet industry: those who believe that calories are all that matter in weight loss, and those who believe that controlling insulin is the key to weight loss.

Caloric Restriction

Many nutritional experts believe that calorie intake is the primary driver of weight control. The formula is simple. If you take in more calories than you burn, you gain weight. If you take in fewer calories, you lose it.

Fat is more calorically dense than other macronutrients. It has nine calories per gram. Protein and carbohydrates each contain four calories per gram, while alcohol contains seven. Therefore, when you restrict fat in your diet, you also restrict caloric intake. Likewise, eating a lower fat diet may prove healthier for the heart and blood vessels by controlling blood lipids (cholesterol and triglycerides) and lowering blood pressure.

Carbohydrate Restriction

Some nutritional experts, such as Dr. Michael Eades, disagree with the calorie hypothesis. They believe the key to weight control lies in minimizing the number of refined carbohydrates you eat, instead relying on protein as the primary source of nutrition. The reasoning behind recommending carbohydrate restriction and increased protein intake is twofold:

  1. Protein does not cause a spike in blood glucose in the same way refined carbohydrates do. Author Gary Taubes explains in the New York Times article, "What if It's All Been a Big Fat Lie" that by regulating blood sugar, your body is less likely to release insulin into your bloodstream. Insulin is your body's primary fat storage hormone, and when it is present in the blood, your fat cells are incapable of releasing their stored energy. When you control insulin by controlling your blood glucose, however, weight loss becomes possible.
  2. Human beings did not evolve to eat refined carbohydrates. Rather, your ancestors ate hunter-gatherer diets consisting of large amounts of proteins and unprocessed plant foods. According to Dr. Kurt Harris, eating the way your ancestors did can help you control your weight and avoid many of the diseases of civilization such as type 2 diabetes.

Who Can Benefit

While this type of diet isn't for everyone, a number of people can benefit from a low-fat, high-protein diet. If any of the following describe you, then this diet might work well for you.

Difficulty Losing Weight on Other Types of Diets

If you don't have any health problems and you have struggled to control your weight on low-calorie diets, then a high-protein, low-fat diet just may work for you. High protein diets that limit refined carbohydrates create a metabolic condition known as "ketosis" in which your body burns fat as its primary source of fuel. Studies show ketosis provides energy and minimizes appetite, two factors that strongly affect the ability to stick to a diet.

Willing to Make a Permanent Change

Since high-protein, low-fat diets help you manage weight by controlling calories and insulin, a return to previous eating habits can lead to rebound weight gain. Therefore, willingness to make a lifestyle change is essential for success.

Want to Manage Diabetes

A 2010 study showed low-carb diets and low-fat diets were both an effective form of weight management for people with diabetes. Another study, conducted in 2004, showed that high-protein, low-carbohydrate diets improved blood glucose levels in people with type 2 diabetes.

Prefer Low-Carb but Worry about Fat Content

Many people are concerned about the high levels of saturated fat that come with many high-protein diets. When you eat animal protein, you also consume saturated fat. According to the Harvard School of Public Health, consumption of large amounts of saturated fats can lead to health problems such as high cholesterol and artery disease.

Eating a low-fat, high-protein diet can help you minimize the amount of saturated fats you consume because you choose naturally lean protein sources.

Contraindications

Some people may not do well on a high-protein, low-fat diet.

People with Kidney Disease

According to the Mayo Clinic, people with kidney disease should avoid high-protein diets, which can aggravate the disease.

People with Kidney Stones

According to the British Medical Journal, high-protein diets can increase the risk of developing kidney stones. If you are prone to kidney stones, a high-protein diet can increase this risk.

People at Risk for Developing Osteoporosis

In The China Study, T. Colin Campbell suggests that eating high levels of animal proteins upsets the acid/base balance in your body because it leads to acidic metabolic residue. Since your body's normal pH is slightly alkaline, it seeks to return to this state. One of the ways it does this, according to Campbell, is by pulling alkalizing minerals from your bones, which can decrease bone density. If you are at risk of developing osteoporosis, talk with your doctor before engaging in a diet high in animal proteins.

Pregnant or Nursing Women

Pregnant and nursing women require a balanced, healthy diet. Studies into the effects of a high-protein, low-fat diet during pregnancy and nursing are mixed.

  • One 2012 study suggested eating a high-protein, low-carbohydrate diet during pregnancy may hamper fetal growth.
  • Another study suggested eating a high-protein, low-carb diet during pregnancy improved the baby's triglycerides and fat metabolism.

If you are pregnant or nursing, talk with your doctor about optimal nutrition.

Implementing the Diet

High-protein, low-fat diets can be safe and effective. If you decide a low-fat, high-protein diet sounds right for you, talk to your health care provider to ensure you don't have any medical issues that may complicate matters.

Basics of Low-Fat, High-Protein Diets