Can a Low Protein Diet Really Help You Lose Weight?

• People online are spreading misinformation with claims that low protein diets are better for longevity and weight loss .
• Experts say adequate protein intake can promote satiety and the development of muscle mass, which are important factors for weight loss.
• A mix of plant-based and animal-based protein sources is best for a healthy diet.

A high protein diet has long been recognized for its weight loss and health benefits. However, misinformation is spreading on social media platforms like TikTok and Reddit that a low protein diet is best.

Proponents claim that we need less protein than previously thought and that reducing your intake could trigger weight loss.

One recent example is a TikTok video that was posted by dietitian @endocrinenutritionist . In the video, she claimed the most compelling argument for a low protein diet is that human breast milk contains just 6% protein and that in the first six months of life, humans double in size.

“Theoricatallicy, that should be all the protein we need,” she said.

Furthermore, she also claimed that the reason we think animal protein is better than plant-based protein is because of “amino acid studies that were done back in the early 1900s on rats.”

However, this particular influencer’s claims are not true.

For example, the nutritional content of breast milk contains 1% protein , not 6%, and a study conducted on older community-dwelling men in 2020 found that low protein intake was associated with a modest increase in risk of all-cause and cause-specific mortality among older men.

Yet a growing number of influencers online are spreading misinformation like this about the benefits and risks of nutrition trends.

The link between low protein diets and weight loss

Kelsey Costa , registered dietitian and science communications officer at Examine , says there has been renewed interest in the notion that restricting protein intake or certain essential amino acids might extend life span .

“ Studies in rodents have also shown that cutting down on protein, without cutting calories, might extend the life span of these animals. However, the evidence is limited and based on animal studies,” she said.

Therefore, these results are not necessarily applicable to humans. Moreover, Costa said any potential benefit of long-term protein restriction is likely offset by an increased risk of sarcopenia , an age-related and progressive loss of muscle and strength.

Dietitian and author of How Not to Eat Ultra-Processed , Nichola Ludlam-Raine , said the shift in popularity from high protein diets to low protein diets reflects a broader understanding of balanced nutrition beyond just macronutrient focus.

However, she said the claim that low protein diets may be better for weight loss is nuanced.

“High protein diets are known to promote satiety, preserve muscle mass during weight loss, and increase thermogenesis,” Ludlam-Raine explains. “On the other hand, lower protein diets could potentially lead to weight loss due to reduced calorie intake if protein-rich, calorie-dense foods are replaced with fruits, vegetables, and whole grains.”

Crucially, though, Ludlam-Raine said that a low protein diet might not be sustainable for everyone as protein is critical for maintaining muscle mass and overall metabolic health.

Similarly, Costa explained how low protein intake may make weight loss difficult in the long term.

“A very low protein diet may initially result in weight loss, likely due to resulting calorie restriction overall, like any other highly restrictive diet,” she said. “But without adequate protein intake, this calorie restriction can result in the loss of both body fat and muscle mass.”

“The loss in muscle mass may ultimately decrease metabolism and lead to further weight regain when the diet is stopped,” she added.

Low protein intake: health benefits and risks

Weight loss aside, you might be wondering how a low protein diet affects overall health and longevity.

Ludlam-Raine said that reduced intake of some proteins, such as red meat, may be linked to increased life span, but this is likely due to the heart health benefits rather than the reduction in protein.

“It’s important to remember that protein is essential for life, with a minimal requirement of at least 0.8g of protein per Kg of body weight a day,” she notes.

Another potential benefit may be disease prevention, especially for some people with pre-existing conditions.

“Lower protein intake has been associated with reduced risks of certain diseases, such as kidney disease (in those with uncontrolled diabetes) and some cancers in certain people – particularly those who may eat a lot of processed red meat ,” Ludlam-Raine explains.

“However, these benefits largely depend on the quality and source of the proteins, as well as the overall diet composition,” she points out.

There are also notable risks with eating a low protein diet.

“Inadequate protein can lead to muscle atrophy , particularly in older adults,” says Ludlam-Raine.

It can also cause nutrient deficiencies. “Proteins are essential for providing certain vitamins and minerals, and a low protein diet may result in deficiencies in nutrients like B12, iron, and zinc,” she explains.

Additionally, a weakened immune function may be another by-product of low protein intake.

“Proteins are crucial for the immune system, and insufficient intake can impair the immune response,” Ludlam-Raine explains.

Healthy protein types

As is often the case with nutrition, how much of a specific nutrient you need is highly individual.

“The recommended daily intake of protein varies by age, sex, and activity level,” says Ludlam-Raine.

“Generally, 0.8 grams of protein per kilogram of body weight is sufficient for most adults, while athletes and older adults may require more, around 1.0 to 2.0 grams per kilogram.”

The kind of protein you eat matters, too.

Protein sources can be divided into:

Animal Proteins: Meat, poultry, fish, eggs, and dairy

“These are complete proteins containing all the essential amino acids that we need.

“They are beneficial for muscle mass maintenance and overall health due to essential nutrients such as vitamin B12 and calcium as well as iodine, but should be consumed in moderation in comparison to plant-proteins,” says Ludlam-Raine.

Plant Proteins: Beans, lentils, tofu, tempeh, nuts, seeds, and whole grains

While some plant proteins may be incomplete, Ludlam-Raine said they can be “combined to provide all essential amino acids (think beans on toast).”

“They are generally lower in saturated fat and therefore can be beneficial for heart health and weight management,” she said.

Processed Proteins: Protein bars, shakes, and other supplements

While convenient, Ludlam-Raine says many of these are technically classed as ultra-processed and should not replace whole foods. She recommends choosing healthier versions of protein supplements that don’t contain added sugar.

To ensure adequate protein intake, Ludlam-Raine recommends including protein at every meal and choosing protein-based snacks.

“It’s a good idea to mix plant and animal protein sources to ensure a variety of amino acids and other nutrients,” she adds.

Takeaway

Eating a very low protein diet isn’t beneficial for health or achieving sustainable weight loss.

For most people, it’s best to eat around 0.8 grams of protein per kilogram of body weight.

Including both animal-based and plant-based protein sources will provide the most benefit.