How much protein is right for you?

BioLounge Staff

Protein's surge in popularity is accompanied by a cacophony of conflicting opinions regarding its health implications. Let's delve into the intricacies to understand the true impact of too much or too little protein and how you can find your sweet spot.

In the ongoing debate about dietary protein, two distinct viewpoints have emerged: one advocating for protein restriction to enhance longevity and another promoting higher protein intake for muscle preservation, metabolic health, and combatting age-related muscle loss.

To define terms, low-protein advocates typically recommend the Recommended Dietary Allowance (RDA) or less, which is currently set at 0.8g/kg of body weight and high protein advocates typically promote intakes ranging from 1.2 to 2.2 g/kg, depending on a variety of factors. For context, a trainer advising 1g of protein per pound of body weight is suggesting the upper limit of 2.2 g/kg.

The Argument for Protein Restriction

Prominent longevity researchers like Dr. Valter Longo and Dr. Morgan Levine have focused on protein restriction as a tactic for lifespan extension. They argue that low protein diets decrease levels of IGF-1 and mTOR signaling—pathways associated with aging and disease development. Their research suggests that by down-regulating these pathways through dietary protein restriction, individuals may experience potential benefits for longevity and healthspan.

Several lines of evidence align with their perspective including:

Reduced Disease Risk: High protein intake, particularly from animal sources, is linked to higher rates of cancer, diabetes, and overall mortality.1
Lifespan Extension: Research in various model organisms shows that reducing protein intake can lead to significant lifespan extensions. For example, inhibiting the GHR-IGF-I axis and mTOR/S6K signaling in rodents not only extends lifespan but also reduces age-related diseases.2
Beyond model organisms, there exists compelling supportive evidence that certain populations with genetically lower levels of IGF-I have fewer chronic conditions and a longer lifespan, suggesting that lower IGF-1 levels as a result of lower protein intake might mimic these beneficial effects.1

However, it's worth noting that Dr. Longo advises increasing protein intake after the age of 65 to counter age-related sarcopenia and frailty, indicating a nuanced approach to protein consumption. In addition, it's essential that we factor in insulin and glucose levels for a full picture of metabolic risk.

Given all of these compelling arguments, why is every wellness influencer now recommending high protein intake?

The Argument for Higher Protein Intake

On the other hand, advocates for higher protein intake emphasize its critical role in maintaining muscle mass, promoting metabolic health, and aiding in effective weight management.3 This perspective highlights the benefits of increased satiety, lean muscle mass preservation, and improved glucose metabolism associated with protein-rich diets.

Additionally, from a healthspan perspective, increased protein intake is essential for older adults to maintain muscle mass and strength, which crucial for preventing sarcopenia, combatting frailty, and maintaining functional independence. This is due to a phenomen known as the anabolic resistance of aging, where with age, muscle requires more of a stimulus, via both resistance training and protein intake to gain the same effect.4 Similarly, increased protein intake is crucial for women during the menopausal transition, another period of anabolic resistance.5

Several lines of evidence support this perspective including:

Muscle Health: Higher protein intake helps mitigate the loss of lean body mass, particularly important during calorie restriction and aging.6
Weight Management and Satiety: Protein-rich diets enhance satiety, which helps regulate energy intake and maintain weight, making them especially beneficial for those trying to lose or manage their weight.7
Metabolic Benefits: Elevated protein consumption supports better metabolic outcomes, including improved glucose regulation and lipid profiles.3

Our recommendation? Aim for a generally higher protein intake, adjusting for your age and activity level, but also incorporate periodic protein restriction for longevity benefits. This combination offers the best of both worlds: supporting muscle preservation, metabolic health, and weight management, while also tapping into the potential longevity benefits of protein restriction.

You can achieve this through intermittent strategies like the Fasting Mimicking Diet, such as ProLon, which temporarily lowers protein intake to activate cellular rejuvenation pathways.

The rest of the time aim for 1.2 -1.6 g/kg of protein, leaning towards the higher end for athletes, those seeking weight loss, or individuals over 65. Emphasize plant-based protein sources during high intake phases and monitor insulin and IGF-1 levels to align with longevity goals.

If you need more guidance, schedule with one of our clinical nutritionists for a personalized nutrition plan here.

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