High protein diets may greatly reduce testosterone levels in men

High protein diets may greatly reduce testosterone levels in men

High protein diets may greatly reduce testosterone levels in men

Somehow, low-carb diets, high-protein diets, ketogenic diets and some other emerging diets have infiltrated our lives, and many weight loss, fitness and health bloggers are touting how good high-protein diets are.

Indeed, high protein diets can help dieters successfully drop the scales in a short period of time. And protein, shakes, milk, lean meats, beef, etc. are equally popular among fitness and muscle building people.

Not only that, but high-protein diets are also popular and recognized by many stars and celebrities, but even so, are high-protein diets really good for us?

High protein diets may greatly reduce testosterone levels in men
High protein diets may greatly reduce testosterone levels in men

Just as people continue to tout high-protein diets, a newly published study has raised alarm bells.

The study reports that reducing carbohydrate intake comes at a cost, as a high-protein diet is likely to lower testosterone levels in men, leading to lower sperm counts and even erectile dysfunction.

The study, published in 2022 in the journal Nutrition and Health, is entitled “Low-carbohydrate diets and men’s cortisol and testosterone: Systematic review and meta-analysis“.

Low-carbohydrate diets and men's cortisol and testosterone: Systematic review and meta-analysis
Low-carbohydrate diets and men’s cortisol and testosterone: Systematic review and meta-analysis

A total of 27 studies involving 309 participants were included in this review. Inclusion criteria were: intervention studies, healthy adult males, and low-carbohydrate diets: ≤35% carbohydrate.

Researchers used Cochrane’s Risk of Bias tool for quality assessment and Review Manager for random effects, meta-analysis using standardized mean differences and 95% confidence intervals for diet duration, protein intake, and exercise duration for subgroup analysis.

A total of 27 studies involving 309 participants were included in this review. Inclusion criteria were: intervention studies, healthy adult males, and low-carbohydrate diets: ≤35% carbohydrate.

Researchers used Cochrane’s Risk of Bias tool for quality assessment and Review Manager for random effects, meta-analysis using standardized mean differences and 95% confidence intervals for diet duration, protein intake, and exercise duration for subgroup analysis.

The results found that both short-term (<3 weeks) low-carb diets and high-carb diets modestly increased resting cortisol; both low-carb and high-carb diets also resulted in higher post-exercise cortisol levels after prolonged exercise (≥20 min).

In addition, moderate protein (<35%) and low-carb diets did not consistently affect resting total testosterone levels, but high protein (≥35%), low-carb diets greatly reduced resting and post-exercise total testosterone levels.

Accordingly, the researchers concluded that resting as well as post-exercise cortisol levels increased during the first 3 weeks of the low-carb diet, after which resting cortisol returned almost to baseline, while post-exercise cortisol levels remained elevated.

This suggests that too much protein and not enough carbohydrates can lead to increased cortisol levels.

Cortisol is often referred to as the body’s “stress hormone”. High cortisol levels have been shown to suppress immune system function, making people more susceptible to viral or bacterial infections, resulting in colds, flu and even COVID-19 symptoms.

On the other hand, this study also demonstrated that a high-protein diet leads to a significant decrease in resting total testosterone levels. More than 35 percent protein lowers testosterone levels by 37 percent, which is known medically as hypogonadism.

Joseph Whittaker, the lead researcher, said in an interview, “Normally, people only need to consume about 17 percent protein, and diets that cause low testosterone usually contain more than 35 percent protein. For people who consume normal protein, there’s basically nothing to worry about, but for groups on high-protein diets, it’s probably safe to keep protein intake to 25 percent.”

Testosterone levels are tied to our health, and not having enough testosterone increases the risk of heart disease, diabetes and chronic diseases such as Alzheimer’s disease.

Healthy testosterone levels are actually better for strength training, muscle building, and athletic performance than groups with lower testosterone in their bodies.

It is important to note that protein that is consumed but not consumed and then piled up in the body can also lead to “rabbit starvation,” where excess protein in the body is converted to ammonia, a condition known as “protein toxicity” because high levels of ammonia are toxic.

“Rabbit starvation was first discovered by Roman soldiers who were forced to live on rabbits during the siege of Villanueva del Campo, where many of them suffered severe diarrhea and died.

Low-carb diets have become very popular in recent years, but through this study we have learned that low-carb and high-protein diets do have significant drawbacks and pitfalls. However, the researchers said they still need to do further exploration of these findings to determine if this is really a bad thing.