Protein on a low-carb or keto diet

1. What is protein?
2. What does protein do in your body?
3. Guidelines for individualized protein intake
4. What foods should I eat to meet my protein target?
5. Different experts’ views on protein intake
6. Does protein adversely affect blood sugar?
7. The DD protein policy

What is protein?

Protein is made up of several smaller units called amino acids. Although your body is capable of making just over half of the 20 amino acids it needs, there are nine that it can’t make. These are known as the essential amino acids, and they must be consumed in food on a daily basis.²

Animal protein is commonly referred to as “complete protein” because it contains all 9 essential amino acids, with an implication that plant proteins are therefore “incomplete.” The reality is more nuanced. Animal protein sources do contain the essential amino acids in consistently high amounts. Plant proteins also contain each of the 9 essential amino acids but often have quite a bit less of one of the essential amino acids compared to animal protein.³

Keto-friendly animal protein sources include meat, poultry, seafood, eggs and cheese.

Keto-friendly plant protein sources include tofu and soy-based products, as well as most nuts and seeds, although some are higher in carbs than others.

What does protein do in your body?

Protein is a major component of every cell in your body. After you eat protein, it is broken down into individual amino acids, which are incorporated into your muscles and other tissues.

These are just a few of protein’s important functions:

• Muscle repair and growth. The protein in your muscles is normally broken down and rebuilt on a daily basis, and a fresh supply of amino acids is needed for muscle protein synthesis, the creation of new muscle. Consuming adequate dietary protein helps prevent muscle loss, and – when coupled with resistance training – promotes muscle growth.⁴
• Maintaining healthy skin, hair, nails, and bones as well as our internal organs. Although the protein turnover in these structures occurs more slowly than in muscle, new amino acids are required to replace those that become old and damaged over time.
• Creation of hormones and enzymes. Many important hormones – including insulin and growth hormone – are also proteins. Likewise, most enzymes in the human body are proteins. Your body depends on a continuous supply of amino acids to make these vital compounds.

In addition, both clinical experience and scientific studies suggest that getting enough protein can help make weight control easier. This might be because protein can reduce appetite and prevent overeating by triggering hormones that promote feelings of fullness and satisfaction.⁵ Your body also burns more calories digesting protein compared to fat or carbs.⁶

Finally, there is growing evidence that increasing protein in the context of a low-carbohydrate diet lowers liver fat and blood glucose in the absence of any weight change.⁷ And protein can also limit the deposition of fat in the liver under obesigenic conditions such as overfeeding with fructose.⁸

Guidelines for individualized protein intake

Taking into account the different positions among keto and low-carb experts, we recommend a protein intake of 1.2 to 2.0 grams per kg of reference body weight for most people. Protein intake within this range has been shown to preserve muscle mass, improve body composition, and provide other health benefits in people who eat low-carb diets or higher-carb diets.⁹

If you’re near your ideal body weight or very muscular, use your actual weight (in kilograms) to calculate your protein needs. Otherwise, you can use your height – and the chart below – to estimate how much protein you should aim to eat on most days.

This chart represents about the middle of the range of 1.2 to 2.0 g/kg range. You can use the following guidance to customize your own protein intake.

If you want to lose fat mass while building or maintaining lean mass, you may want to maximize your nutrition/protein per calorie. We recommend aiming for the higher end of the range noted earlier in this section, between 1.6 g/kg and 2.0 g/kg. (The chart above represents around 1.6 g/kg.)

In some cases, an even higher protein intake of more than 2.0 grams of protein per kg of body weight may be beneficial, at least temporarily.¹⁰ This would include people who are underweight or healing from illness, injury, or surgery.

On the other hand, individuals who follow keto diets for therapeutic purposes – for instance, for management of certain cancers – may want to aim for the lower end of the range, between 1.2 and 1.5 grams per kg of body weight per day.¹¹ Importantly, this must be done under strict medical supervision.

Muscle protein synthesis declines from the third decade, and the rate of decline increases from age 60 years.¹² Therefore, some experts in protein research believe that older people need a minimum of 1.2 grams per kg daily to counteract muscle loss and other age-related changes.¹³

Aim for at least 20 grams of protein at each meal

Research has suggested that we need at least 15-25 grams of protein at each meal to adequately stimulate muscle protein synthesis.¹⁴

Can you eat too much protein in one meal, thereby “wasting” excess protein instead of digesting and using it to make new proteins? The answer to this question has proven to be surprisingly controversial over the years, but we believe that a careful interpretation of the research shows that the answer is “no.” While the rate of muscle protein synthesis starts to decline at very high protein intakes, the rate of muscle protein breakdown decreases to a much greater extent, leading to a net positive effect on muscle tissue.¹⁵

Further, muscle is not the only tissue in the body that uses dietary amino acids to make proteins. The digestive system also makes proteins, which can be broken down and released into the bloodstream well after a meal, to be used by tissues like muscle to make protein.¹⁶

Therefore, you can see that studies demonstrating that muscle protein synthesis tops out after 30 grams of protein should not be interpreted to mean that we can’t absorb or use more than 30 grams at a meal.¹⁷ The ability of larger amounts of protein to suppress muscle protein breakdown, as well as the ability of the digestive tract to use digested protein to make new protein, will have a net positive effect on muscle growth.

For a more detailed explanation of how muscle responds to different protein intakes, read our guide: Does intermittent fasting cause muscle loss?