High Protein Diet Side Effects

Often promoted for its weight management effects, ability to improve satiety, and the possibility of boosted energy levels, a high protein diet is a popular dietary lifestyle many choose to follow.

During the 1950s, bodybuilding competitions popularized the consumption of high protein diets, and by the 1970s, a slew of modern diet programs focussing on protein intake became mainstream, including the Scarsdale, Atkins, South Beach and Dukan diets.

"Protein is a necessary component for so many of our body’s systems and functions, such as regulating hormones, building muscle, and for our skin, hair, nails and even bones," explains Jaclyn Kiernan, MS, RDN, former Noom Coach and current Lead Coach at MetPro.

The recommended daily protein intake for the average person is 0.8 grams per kilogram of body weight, and consuming more than this amount may be considered a high protein diet, explains Kiernan.

Be mindful, not all protein sources are equal. "Proteins each receive a biological value number, with animal protein sources containing a higher value to plant protein, meaning that you would need to consume a larger quantity of plant based foods to meet your protein needs, compared to animal sources," Kiernan notes.

The Benefits of a High Protein Diet

As mentioned, an individual might turn to a high protein diet as a method for weight management by curbing hunger, as well as for its muscle building effects.

Many studies have scientifically backed these findings, among other benefits, such as:

Can Reduce Fat Mass and Improve Lean Muscle

An overview on various literature by the American Journal of Clinical Nutrition, exploring several meta-analysts of short term, controlled feeding studies, highlights an increase in weight loss, fat mass loss, and a drop in waist circumference for participants. Alongside this, the findings showed a preservation of lean mass with higher protein diets.

Can Lower Triglycerides

A high protein diet may be beneficial to individuals with type 2 diabetes, given its ability to reduce the presence of triglycerides (a fat lipid found in your blood) compared to a low protein diet, thereby possibly reducing the risk of cardiovascular diseases.

Can Repair Tissues

"Protein is also important for repairing tissues, which is why a higher protein diet may be recommended for healing wounds and injuries," says Kiernan. This is due to the body's requirement of protein nutrition as an aid to the wound healing process, which increases the need of calories and proteins at the injured area.

Controversy Surrounding High Protein Diets

While high protein diets are relatively safe for healthy individuals without health implications, it's important to note this diet is not suitable for everyone.

"You should not follow a high protein diet without the guidance of a medical professional—consuming too much protein can be a burden on the body," which, Kiernan says, can lead to undesirable health issues.

What's more, some protein choices are more helpful to the body, given many protein-rich foods from animals can contain unfavorable levels of saturated fats and cholesterol.

Consuming too much protein can also be taxing for the kidneys, and so this pattern of eating has negative characteristics for anyone with a hiked cholesterol count or renal dysfunction. To counterbalance this characteristic, an increase in water intake is required to avoid the risk of dehydration.

Side Effects

As with most diets, there are risk factors and negative side effects to consider before making a drastic change. Additionally, you should speak to a health care professional if you have any hesitations or underlying health issues that a high protein diet may impact.

May Cause Gastrointestinal Issues

"When you consume a high protein diet, you reduce your intake of carbohydrates, which results in a lower intake of fiber," explains Kiernan. In turn, this can lead to gastrointestinal issues including constipation.

Dietary fiber, found in carbohydrate-loaded foods including fruit, vegetables and grains, passes in transit without much of it being absorbed, and therefore adds "bulk" to your stools.

May Cause a Nutritional Deficit

Similarly, a diet high in protein might lack nutritionally-dense foods. Keirnan notes, "It's important to consume a balanced diet by including carbs and healthy fats, regardless if you increase your protein, to meet your body’s nutrition needs and prevent nutritional deficiencies."

In some extreme cases, the body can become flooded with additional protein that is not utilized, in turn causing a metabolic strain on the bones, kidneys, and liver.

Therefore, such a diet may unintentionally reduce the intake of foods containing certain key nutrients, resulting in deprivation of essential vitamins and nutrients.

May Lead to Cardiovascular Problem

"A high protein diet may include an increased intake of red meats and fattier proteins, which can spark cardiovascular issues," outlines Kiernan.

While it's widely understood that red meat is a contributing factor in heart disease, it's relatively unknown that Trimethylamine N-oxide (TMAO), a dietary byproduct from the bacteria in the gut during digestion, may also be a factor. This is due to the increase in cholesterol deposits in the artery wall and how the chemical might activate platelets, in some cases increasing the chances of a heart attack or stroke.

However, not all protein has the same effect on your body. Research spanning 32 prospective cohort studies over a follow-up of 3.5 to 32 years, found that the intake of plant protein was associated with a lower risk of all-cause mortality and cardiovascular disease mortality (although not cancer mortality), suggesting that replacing animal protein with plant protein could be associated with longevity. In fact, a three percent daily intake of plant proteins was found to decrease the risk of death from all causes by five percent.

May Cause Fatigue

Given that carbs are the body's main source of energy, a drastic reduction may cause a drop in stamina. This macronutrient is able to rapidly release energy, such as during intense exercise spells. This explains why this source of fuel is key in the diet of athletes.

In the example of athletes, overloading the body with protein above the recommended intake might reduce the intake of carbs and instead increase fat consumption, resulting in lower muscle glycogen levels and limiting intense exercise output before fatigue sets in.

In tapering your diet accordingly, you may be able to ward off more intense fatigue due to a reduction in carbs.

Other Potential Side Effects

Some further reported studies found side effects of consuming a high protein diet, especially one of a ketogenic nature, to include a greater likelihood of dehydration, electrolyte disturbances,, nausea and headaches.

This research has found limited evidence, so additional investigations are required to conclusively identify such risk factors.

A Word From Verywell

The diet that best suits your body will provide you with sufficient fuel and the nutrients to sustain you. This may be a high protein diet, if following this form of eating generates an energized, active, and healthy body. However, this may not be suitable in the long-term, depending on your motivation, nutritional needs, goals, and budget.

Although a high protein diet can promote potential benefits to a number of health markers, it may not be suitable for every individual, especially those with specific conditions. Make sure you seek advice and guidance from a health care professional before altering your diet.