The question of whether a high protein diet is good or bad for you often comes up when the subject of weight loss is brought up. I’ll tell you right away that it’s not just a simple black and white answer to this question. The truth is that it depends on your body type, activity level, age and gender.
Defining High Protein
According to the 2015–2020 Dietary Guidelines for Americans, protein should represent 10% to 35% of total daily calories. In the United States, the Recommended Dietary Allowance for protein is 46 g per day for women older than 13 and 56 g per day for men older than 18.1 The Institute of Medicine recommends adults get a minimum of 0.8 g protein for every kg of body weight per day.2
According to Christopher Gardner, PhD, director of nutrition studies at the Stanford Prevention Research Center and a research professor of medicine at Stanford University in California, few Americans consume inadequate amounts of protein and, in fact, most consume more than two times their requirements. “Even the ones who aren’t trying to eat a lot of protein tend to eat beyond what they need, often in the form of bars or powders,” Gardner says.
Although there’s no clear definition of a high-protein diet, the upper limit for protein set by the Dietary Reference Intakes is 35% of daily calories; therefore, many practitioners use “35% or more calories from protein” as a defining benchmark.
Connie Diekman, MEd, RD, CSSD, LD, FADA, director of university nutrition at Washington University in St. Louis, and a former president of the Academy of Nutrition and Dietetics, considers a diet that includes more protein than carbohydrates to be a high-protein diet. Typically, such diets provide more than 35% of calories from protein. However, she says, “The need for protein can vary among individuals. Body builders need more than cross-country runners, and pregnant women need more than when they’re not pregnant. It’s a bit difficult to give a clear definition.”
Do They Really Promote Weight Loss?
After decades of health professionals promoting a low-fat dietary approach to weight loss, research currently is providing evidence that a high-protein diet may be an effective approach. A meta-analysis of 24 studies published in The American Journal of Clinical Nutrition examined the effect of the macronutrient profile of diet on weight loss.3 Compared with an energy-restricted standard-protein diet, an isocalorically prescribed higher-protein diet aided in greater weight loss. In addition, high-protein diets were found to be more effective than lower-protein diets for preserving muscle mass and preventing metabolic slowdown during weight loss.
Some research has shown that high-protein diets may impact people differently. Whether this is due to taste preferences or genetics remains to be determined. A European study published in the International Journal of Obesity concluded that based on different gene types, high-protein diets are effective for weight loss and maintenance in 67% of the population.4 Results from the A TO Z study, which compared the Atkins, Zone, Ornish, and LEARN diets, showed variation in weight outcomes within each.5 More research is needed to understand this concept of high-protein diets and nutrigenomics.
What does protein do to your body? Here are some of the top benefits of a high-protein diet:
1. Boosts Muscle Mass
Including plenty of foods high in protein in your diet is necessary to build and maintain healthy muscle mass, while also supporting tendon, ligaments and other body tissue. While high-protein foods are important for bodybuilding, they are also necessary for developing leaner muscles.
When your diet is lacking in amino acids, “muscle wasting” (or muscle atrophy) can take place when your muscle fibers are broken down to support your body’s energy needs.
High-protein foods are especially important after exercise, since physical activity like strength training purposefully damages muscle tissues so they can repair and grow back stronger. For the process to happen effectively, you need some extra protein to help repair the damage.
While protein alone won’t enhance athletic performance, research shows that eating protein benefits performance when eaten before and after exercise. It helps increase muscle recovery, promotes muscle synthesis and serves as effective muscle ache treatment.
2. Helps Manage Your Weight by Filling You Up
Although some research studies show conflicting results regarding high-protein diets versus low-protein diets for maintaining an ideal weight or losing weight fast, there’s plenty evidence that protein helps make you feel full and can prevent overeating.
Studies show that controlled calorie intake in association with a moderately high protein intake can be an effective and practical weight-loss strategy.
Some of the reasons this is true? Protein functions to increase satiety to a greater extent than carbohydrates or fats, helping prevent overeating and snacking.
It’s usually much easier to overeat carbohydrates, especially if they’re refined or sweetened, than it is to overeat healthy protein foods.
Eating protein also creates a process in the body known as thermogenesis, which requires the body to expend more energy (calories) in order to digest food. At the same time, protein helps ward off muscle loss that can result from a low-calorie diet, which makes certain protein foods beneficial for weight loss.
3. Stabilizes Blood Sugar Levels
Insulin is a hormone that’s required for carbohydrates, fat and protein to be metabolized. However, carbohydrates require much more insulin than fat or protein.
The major determinate of blood sugar levels is the glycemic index response from the foods you eat, so while eating high-carb and high-sugar foods results in fluctuations in blood sugar levels, eating high-protein foods does the opposite.
Eating foods with protein has a minimal effect on blood glucose levels and can, in fact, slow down the absorption of sugar during a meal. This means a low-carb, high-protein diet can help prevent spikes in blood glucose, which is especially important for preventing type 2 diabetes, balancing energy levels, and keeping your appetite and mood in check.
4. Improves Your Mood
Certain amino acids from high-protein foods are needed to balance hormones naturally, control your mood and act as a natural treatment for anxiety. According to studies, proteins help neurotransmitters function and synthesize hormones like dopamine and serotonin that calm us and keep our outlook positive.
Many people who are lacking in key amino acids start experiencing weakness, moodiness, and increased anxiety or signs of depression for this reason. Because protein helps stabilize glucose in your blood, it also prevents mood changes, irritability and cravings that can occur due to fluctuating blood sugar levels.
5. Promotes Healthy Brain Function and Learning
Proteins are needed to make enzymes, hormones and neurotransmitters that are critical for cognitive function. As your mother may have told you when you were a kid, eating a healthy breakfast sets the tone for the day and prepares you to learn and remember information.
The brain requires a steady supply of amino acids in order to keep concentration, focus and energy levels up. Studies show that when amino acid deprivation takes place, learning and coordination suffers, but once all necessary amino acids are reintroduced into the diet, learning and motor skills improve.
6. Helps Maintain Strong Bones
Many studies now show that a positive association exists between eating more foods with protein and better bone health. The effects of protein on bones also relate to the specific high-protein foods eaten and intake of important bone-building nutrients like calcium and magnesium.
A diet high in protein from whole, nutrient-rich foods can help heal broken bones and prevent bone weakness, fractures and even osteoporosis by increasing calcium absorption and helping with bone metabolism.
Recent studies on the elderly in the U.S. show that the greatest bone losses occur in people with low protein intake of 16–50 grams per day. It’s believed that when someone eats a low level of protein, insulin-like growth factor production is reduced, which in turn has a negative effect on calcium and phosphate metabolism in the bones and bone formation.
7. Protects Heart Health
Some studies show that an inverse relationship between protein intake and risk of heart disease has been observed in adults, as higher protein diets appear to be one of the natural remedies for high blood pressure. Also, substituting carbohydrate foods with protein results in lower LDL “bad” cholesterol and triglyceride levels.
One reason this might be true is because higher protein diets balance blood sugar and tend to help prevent other heart disease-related causes, including obesity and diabetes.
8. Slows Aging and Promotes Longevity
One of the key roles of high-protein foods is helping the body synthesize glutathione, often called the “master antioxidant.” Glutathione is stored within our own cells and helps us detox and reduce carcinogens that age us.
Animal and human studies both show that adequate protein intake is crucial for the maintenance of glutathione and helps the body stay in a state of balanced “homeostasis.”
Glutathione deficiency contributes to oxidative stress, which plays a key role in age-related diseases like Alzheimer’s disease, Parkinson’s disease, liver disease, cystic fibrosis, sickle cell anemia, cancer and viral infections.
Research shows that diets that include enough foods that are high in protein can help treat muscle loss due to aging (called sarcopenia). A diet that has adequate levels of protein helps slow the aging process by keeping muscle mass intact, supporting strong bones, and maintaining high cognitive and immune function.
In the elderly, amino acid deficiencies can potentially lead to eye problems like cataracts, heart problems, muscle loss, weakness and mood changes.
As you age, your body is less capable of synthesizing amino acids on its own, which is one reason why the amount of muscle you have tends to decrease over the years while fat accumulates. This makes it even more important for you to eat plenty of protein-rich foods to support not only a healthy body weight, but to keep your memory sharp, energy up, and strength and balance in place.
Deciphering the Theories
Weight loss experts have proposed various theories on why high-protein diets may help certain individuals shed pounds. One theory is that they decrease hunger and promote satiety. It’s believed that higher protein intake may increase production of peptide YY and glucagonlike peptide 1 (GLP-1), hormones that help promote the feeling of fullness. In a controlled study of 12 healthy women, the group that consumed a high-protein diet experienced higher GLP-1 levels, greater feelings of fullness, and less hunger than the group that ate a lower-protein diet.6 Studies also have found that higher protein intake helps reduce levels of ghrelin, aka “the hunger hormone.” A study of 15 healthy men showed consumption of a high-protein meal to have greater suppression of ghrelin compared with consumption of a high-carbohydrate meal.
Another theory is that a high-protein diet may significantly increase the rate of metabolism or have a higher diet-induced thermogenesis, a metabolic response to food. Food intake results in a brief increase in energy expenditure attributable to the various steps of nutrient processing (eg, digestion, absorption, transport, metabolism, and storage of nutrients). Research using a room calorimeter to assess 24-hour energy expenditure in subjects found higher energy expenditure (71 kcal per day) in those consuming a high-protein diet.8 Other findings have reported that subjects following a diet containing 29% protein had a higher resting metabolic rate, burning 213 more kcal per day than those consuming the same calories with 11% energy from protein. According to a report by Frank Hu, MD, PhD, MPH, the Frederick J. Stare Professor of Nutrition and Epidemiology at Harvard T.H. Chan School of Public Health in Boston, “The synthesis of protein, the high ATP [adenosine triphosphate] cost of peptide bond synthesis, as well as the high cost of urea production and gluconeogenesis are possible reasons for the higher thermic effect of protein.”9 However, Hu notes that most of the studies on high-protein diets and weight loss have been too short in duration to be conclusive.
Nonetheless, studies have shown that high-protein diets may help preserve lean body mass during weight loss. Researchers from the School of Sport and Exercise Sciences at the University of Birmingham in the United Kingdom investigated the influence of dietary protein on lean body mass loss and performance during short-term weight loss in 20 young, healthy athletes.10 They found that a diet composed of 35% protein was significantly superior to a 15% protein diet for maintenance of lean body mass.
While some studies have suggested the validity of these theories, additional research is needed to understand the actual mechanism. Gardner believes the findings based on these theories are trivial and isn’t convinced. “I don’t think there’s sufficient research supporting the idea that you burn extra calories when metabolizing protein, or that eating protein leads to building more muscle, and lean tissue burns more energy than fat,” Gardner says, pointing to a study published in the Journal of the American Dietetic Association that found that varying the
What is Protein and What Makes a Meal High-Protein?
Protein is abundant throughout our bodies and provides the building blocks for muscle, hair, skin, bone, and body tissue in general. Even hemoglobin that carries oxygen throughout the body via the bloodstream relies on protein.
Protein encompasses 22 amino acids, and the nine essential amino acids, including histidine and lysine, must come from the foods we eat. A daily supply is needed for the body to function correctly, and protein aids in wound healing, the production of cells, and the growth and repair of muscles. It is also the catalyst for the production of enzymes and hormones, and it helps with many other bodily functions.
An inadequate supply of protein can result in muscle loss, general weakness, and malnutrition. However, most people in the Western world have access to adequate amounts of protein-containing foods, and malnutrition from protein deficiency is rare.
If you follow a high-protein diet, a typical meal will not be balanced. Instead, the scales would tip in favor of high-protein-containing foods, such as meat, fish, legumes, beans, and eggs. These would be consumed at the expense of carbs like bread, rice, pasta, and vegetables. In addition, foods high in healthy fats like avocados, olive oil, and cheese would also be put on the back burner.
Although your meals should be balanced, many people thrive from including more protein in their diet. Take a look at these five reasons why a high-protein diet may be right for you.
High-Protein Foods to Add to Your Diet
High-protein diets do not need to be bland just because they are lower in fat, carbs, and sugar. Many high-protein foods are both delicious and healthy! While you may want to dive right in with these tasty foods, increase your protein intake slowly so your body has time to adapt. Here are some of the best high-protein foods you may want to slowly introduce into your diet.
- Chicken breast is fat-free and high in protein, and a 200-gram serving contains 62 grams of protein.
- Fresh Mackerel is high in healthy omega-3 fatty acids and protein, and 100 grams contains 19 grams of protein.
- Chickpeas are full of fiber and a great source of protein for vegetarians, and 100 grams contains 19 grams of protein.
- Lean steak is a good source of highly absorbable iron, and its protein content is impressive too! 100 grams contains 25 grams of protein
- Eggs contain vitamins such as B12 and Vitamin D, and 100 grams contains 13 grams of protein. Making eggs is a quick and tasty way of getting a protein boost!
Should You Have a High Protein Diet?
Protein is vital to the body and is required for many different bodily functions. Everyone has different daily protein requirements depending on age, weight, and lifestyle.
However, individuals on high-protein diets that allow them to eat more protein than the daily allowance states can experience many benefits such as weight loss, increased muscle mass, lower body fat percentages, and reduced chances of developing diabetes.