How Peter Attia Eats for a Longer Life

Dietary restriction

“Dietary restriction (DR) is probably the most common strategy employed for reducing energy intake. It is conceptually simple: pick a type of food and then don’t eat that food,” explains Attia. He clarifies the type of food you pick matters—it should be calorically dense. For example, cutting out lettuce isn’t going to do anything; whereas, cutting out soda, sugary drinks, and added sugar will make a big impact.

“A more significant issue with DR is that everyone’s metabolism is different. Some people will lose tremendous amounts of weight and improve their metabolic markers on a low-carbohydrate or ketogenic diet, while others still will actually gain weight and see their lipid markers go haywire—on the exact same diet,” he explains. “Conversely, some people might lose weight on a low-fat diet, while others will gain weight.”

A better way, he suggests, is manipulating the four macronutrients—alcohol, carbohydrates, protein, and fats—optimally for you. According to Attia, the specific split needs to be personal to be effective. In other words: experiment until you find what works for you.

Time restriction

Also known as intermittent fasting, time restriction (TR) is the easiest way to cut calories, according to Attia. Time-restricted eating involves eating for a set period of time, and then intentionally fasting for a set period of time. It can revolve around a 24-hour clock, like 18:6 intermittent fasting—which involves fasting for 18 hours and eating for six—or can involve a more extended time period like a four-day fast (what Attia challenged Chris Hemsworth to do in National Geographic’s docuseries Limitless).

Fasting sounds simple, but like dietary restriction, TR doesn’t always work. “This can still backfire if you overeat,” warns Attia. The TL;DR: it’s not permission to eat as much pizza and ice cream as you can put back.

“If we are going to use a powerful tool like fasting, we must do so carefully and deliberately,” he says. Timing matters. You could skip breakfast or dinner to shorten your eating window, “but in my view, sixteen hours without food simply isn’t long enough to activate autophagy, inhibit chronic mTOR elevation (mTOR is a gene that regulates protein production and helps you build muscle, but too much is linked to diseases like diabetes and cancer (2, 3)), or engage any other longer-term benefits of fasting we would want to obtain,” he adds.

And fasting for longer periods comes at a price. “You are virtually guaranteed to miss your protein intake with this approach,” he says. “One not uncommon scenario that we see with TR is that a person loses weight on the scale, but their body composition alters for worse: they lose lean mass (muscle) while their body fat stays the same or even increases,” says Attia.

Attia typically reserves fasting-based interventions for more extreme clients, who can tolerate more intense fasting regimens (and the subsequent loss of muscle) because they’re losing so much fat at the same time. He also monitors protein intake carefully. “My rule of thumb for any eating pattern is that you must eat enough to maintain lean mass (muscle) and long-term activity patterns,” he adds.