Is a Low-Protein Diet Better For Longevity or Weight Loss?

Julia Malacoff
by Julia Malacoff
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Is a Low-Protein Diet Better For Longevity or Weight Loss?

healthy diet and regular exercise have been shown to decrease the risk of heart disease, mental decline and other illnesses and help promote longevity. Now, thanks to the popularity of recent Netflix documentaries and social media, diets claiming to help prolong your life, like the Blue Zone Diet and the Longevity Diet, are experiencing a spike in interest.

The hallmarks of these eating styles are what you’d expect out of any health-focused diet: More whole foods, fewer highly refined foods, and lots of plant-based staples. Notably, they’re based on observations about communities where people routinely live past 100. “It’s actually a lifestyle,” says Donna Rose, a registered dietitian. “Centenarians in a small town in Italy consume a diet that includes mainly pasta and vegetables. They do not eat a lot of meat, and consequently have a lower protein intake,” she explains.

HOW MUCH PROTEIN SHOULD YOU CONSUME?

This might be surprising or even confusing, given that high-protein diets are popular (and often recommended by nutrition experts) for people looking to lose weight, increase their athletic performance, or improve their overall health. For instance, general protein recommendations for a healthy adult sit at about 0.8 grams/kg of body weight per day, or between 1.2–2.0g/kg of body weight per day for active adults. So, for a 160-pound person (72.5kg), that would mean somewhere between 58 grams (for someone non-active) and 145 grams (for someone very active) of protein per day.

The Blue Zone Diet isn’t super specific about protein numbers, but says 95% of your food should come from plants, while 5% can come from meat (1–2 times per week) and fish (up to 3 times per week). Certainly, it’s possible to get plenty of protein from plants, but requires careful planning.

The Longevity Diet is more specific around protein. The guidelines state adults under age 65 should keep their protein to 0.31–0.36 grams per pound of body weight. So, as an upper limit, a 160-pound person would be eating 58 grams of protein a day — the bare minimum recommendation for sedentary adults.

WHAT YOU NEED TO KNOW ABOUT LOW-PROTEIN DIETS

So, are low-protein diets like this healthy? Well, like pretty much everything else in nutrition, it depends. Here’s what you need to know before you try it:

1. PRIORITIZING PLANT-BASED FOODS IS IDEAL FOR HEALTH

“The research is pretty clear that a diet high in animal products, and high in saturated fats, leads to obesity and increases the risk of cancer and heart disease,” says Rose. “In that regard, a plant-based diet is a healthier way to eat and could therefore promote longevity.”

But, while the research strongly supports the benefits of plant-based eating, this is in light of eating adequate protein as well, says Elizabeth Merrill, a registered dietitian nutritionist. So, if you do decide to try it, it may be smart to stick to the higher end of the protein recommendations.

2. GOING TOO LOW IN PROTEIN IS NOT GREAT FOR WEIGHT MANAGEMENT

“In general, a lower protein diet, which by definition may be 4–8% of daily calories, is not ideal,” says Merrill. High-protein diets are often recommended for people who want to lose or manage their weight, since protein is highly satiating and helps retain lean muscle mass.

Lower protein diets will, by default, be higher in carbohydrates and fat. “Although fat as a macronutrient is more dense per gram and also satiating, it does not take as long to digest, nor require as high of metabolic demand to burn,” Merrill explains. “In short, it is much easier to over-consume fat sources than protein, which could hamper weight loss.”

3. HIGH-CARBOHYDRATE DIETS MIGHT NOT BE IDEAL FOR EVERYONE

“Eating in this way will likely lead to increased carbohydrate intake, which may lead to unsteady blood sugar levels, varying energy levels, and perhaps increased appetite,” says Merrill. While it’s definitely possible to eat a plant-based diet that is not high in carbohydrates, both The Blue Zone Diet and The Longevity Diet emphasize them.

4. ON THE OTHER HAND, SOME PEOPLE EAT WAY MORE PROTEIN THAN THEY NEED

“In the typical American diet, protein is the star,” says Julie Harrington, a registered dietitian. “While protein plays a vital role, many are overconsuming this one macronutrient.” Particularly for people who are not active and eating way more protein than they need, cutting down on protein may help them make more room for plant foods containing vital micronutrients and phytochemicals they’d otherwise be missing.

5. THE LONGEVITY DIET IS ABOUT MORE THAN JUST WHAT YOU EAT

Those centenarians mentioned earlier “also do a lot of walking, include a glass or two of wine and live a low-stress life,” notes Rose. So, while eating lower protein might make this diet less than ideal for certain people, there are definitely other elements of this lifestyle [such as being active and cutting back on stress] that most people benefit from.

6. FOR SOME, THESE EATING STYLES MAY BE TOO RESTRICTIVE

“While plant-based eating has numerous benefits for health in general, any eating style with strict food rules is generally not sustainable for most people,” Merrill points out. When it comes to eating healthier, what matters most is what you can stick with consistently.

THE BOTTOM LINE

“The biggest overall question you need to ask yourself before starting one of these diets is ‘why?’” says Leslie Urbas, a registered dietitian and personal trainer. Are you using it because it’s trendy, or because you want to take on this lifestyle long term?

“Changing your diet from higher protein to low protein, no animal products and increased fruits and vegetables can be challenging and should not be taken lightly as a way to lose weight rapidly,” she adds. “Someone attempting to start these types of diet should seek expert nutrition advice and counseling to ensure this is the best decision for their lifestyle.”

It’s also important to note that living longer isn’t just about what you eat, Rose says: “Longevity encompasses a lifestyle that includes not only diet, but also healthy habits, a positive attitude and genetics.”

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About the Author

Julia Malacoff
Julia Malacoff

Julia (@jmalacoff) is a seasoned writer and editor who focuses on fitness, nutrition, and health. She’s also a certified personal trainer and Precision Nutrition Level 1 coach. Based in Amsterdam, she bikes every day and travels around the world in search of tough sweat sessions and the best vegetarian fare.

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