Peter Attia on fasting: What protocol does he follow now?

Dr. Peter Attia’s approach to health and longevity, detailed in his book Outlive, is marked by a commitment to continuously learning and adapting. He keeps revising and refining his strategies as he uncovers new information during his research or his understanding of health principles deepens.

His take on fasting is no exception. Although he has explored many dietary and fasting protocols over the years — from strict ketogenic diets and extended water fasts to various forms of intermittent fasting — his current fasting practices are less rigid and less frequent. 

In this article, we examine Peter Attia’s fasting regimen, reviewing how it has evolved and the key principles that guide it. 

Does Peter Attia still fast?

Yes, Peter Attia still incorporates fasting into his routine, but it’s no longer as rigid or extended as it used to be. He transitioned from the multi-day water fasts and lengthy daily time-restricted fasts he engaged in from 2011 to 2020 and now takes a more flexible and personalized approach.

What Peter Attia’s fasting schedule looked like in the past

Source: Ivan Samkov

Attia’s previous fasting regimen, especially when he focused on it extensively, involved two main approaches: 

1. Extended water fasts: Attia explored multi-day water fasts at different intervals during the year. He would do a seven-day water-only fast once per quarter and a three-day water-only fast once a month. 

2. Time-restricted diet (or intermittent fasting): He experimented with different time-restricted eating windows, often confining his meal time to a specific period during the day. He explored the shorter eating frame — 16:8, where you fast for 16 hours and eat within eight hours, but eventually reached a peak of a 22:2 eating window, eating within only two hours during the day. 

Attia engaged in these extensive fasting regimens for their potential benefits, including stimulating autophagy and triggering a metabolic reset. However, he no longer pushes himself to such extremes, having recognized the risks of his past routines, particularly muscle mass loss (a critical factor for longevity and healthy aging). 

[Youtube](https://youtu.be/Tb6gMegtLcg)

The benefits and risks of fasting, according to Peter Attia

Attia notes that while fasting has some key benefits, it’s often difficult to gauge its effects at a cellular level. Its benefits are also not without their downsides, so let’s explore his views on the benefits and risks of fasting.

The potential benefits of fasting

According to Attia, fasting has the following benefits:

1. Metabolic health improvement: Fasting can influence metabolic processes in several ways. For instance, it can affect insulin sensitivity, blood sugar regulation, and the balance of various metabolism-related hormones. Attia explored fasting for its potential to reset metabolic pathways and reduce the risk of diseases like type 2 diabetes. He believes fasting can be useful for improving metabolic health but should be part of a comprehensive approach that includes regular exercise and diet.

2. Cellular autophagy: Autophagy is one of the key benefits of fasting, according to Peter Attia. It’s a cellular process where the body triggers starvation ketosis — it burns fat stores to keep you from feeling hungry and clears out damaged or dysfunctional components. Attia believes fasting may be one way to promote autophagy, but more extensive research is needed to understand the optimal fasting protocols to achieve this.

3. Longevity: Studies show that fasting may promote longevity by influencing cellular aging and disease risk factors. A frequent 12–48-hour fast may help protect cells, repair damage, and remove dysfunctional components. Still, Attia emphasizes that this research is still evolving, and while it does have potential benefits, it’s one factor among many. Instead, he suggests optimizing sleep and diet, managing stress, and incorporating other lifestyle modifications to increase lifespan.

Source: Chokniti Khongchum

The potential risks and downsides of fasting

After following a strict fasting schedule for years, Attia began to discover critical risks and downsides to his routine that could affect lifespan and healthspan. Here are the most notable ones:

1. Muscle mass loss: During fasting, the body can break down muscle tissue for energy if it lacks sufficient fuel. Attia experienced muscle loss during his extended fasting periods, and this remains one of his major concerns. He believes muscle mass is essential for longevity because it supports continued physical activity as we age. To minimize muscle loss during fasting, he advocates prioritizing adequate protein intake and performing strength training exercises regularly.

2. Nutrient deficiencies: Restricting your food intake, especially during extended fasts, can increase the risk of not getting enough essential nutrients like protein, vitamins, and minerals. Attia emphasizes the importance of carefully planning your fast to avoid these risks. If you’re engaging in an extended fast, he suggests being mindful of nutrient intake and using supplements to compensate with the guidance of a medical practitioner. 

3. Individual variability: Attia believes that there is no one-size-fits-all approach to fasting. Different factors affect the way people respond to a fast, including genetics, health status, lifestyle, etc. He recommends that fasting protocols be highly individualized and tailored to one’s needs. An ideal fasting candidate, according to him, is someone with muscle to spare or someone with over 35% body fat. 

Dr. Peter Attia’s fasting schedule: What he’s doing now

Dr. Attia doesn’t prescribe a specific or fixed intermittent fasting schedule but prioritizes flexibility and pays attention to his body’s signals when deciding when to fast. He notes that he hasn't engaged in a multi-day fast since 2020. Instead, he now favors shorter, more manageable fasting periods, and his fasting windows and frequency vary. He focuses less on the timing of the fast and more on the quality of his diet, ensuring he consumes:

• 2700–2800 calories per day

• 1 g of protein per lb of body weight (2.2 g per kg)

Attia views fasting as a tool that he uses strategically in alignment with his current goals. He believes shorter, less frequent fasts are more practical and sustainable for most individuals, especially when combined with a healthy diet and regular workouts. 

Here’s a table highlighting the key differences between Attia’s past and current approach to fasting:

| Category           | Past approach                                 | Current approach                                   |
| ------------------ | --------------------------------------------- | -------------------------------------------------- |
| Fasting modalities | Extended water fasts and various IF protocols | Flexible, personalized version of IF               |
| Fasting lengths    | Longer multi-day fasts                        | Shorter single-day fasts                           |
| Frequency          | Frequently (daily and monthly)                | Occasionally, based on needs                       |
| Emphasis           | Meal timing                                   | Food quality (protein) and overall caloric balance |
| Rigidity           | Structured and rigid                          | Flexible and adaptable                             |
| Key concerns       | Autophagy, metabolic health, etc.             | Muscle loss prevention, personalization

As seen in the table, Attia’s fasting evolution highlights the importance of adapting health strategies to individual needs and prioritizing long-term sustainability. 

Attia’s guide to muscle preservation during fasting

In a discussion with celebrity trainer Thomas DeLauer, Attia recommended an occasional 20–24-hour fast as the best approach to fasting without losing muscle. In his book Outlive, he says that you can achieve ideal retention results by sandwiching your fast with dialed-in protein intake. This helps stimulate muscle protein synthesis (MPS), minimizing the risk of muscle loss and optimizing muscle recovery. 

As a rule, he suggests eating enough protein to maintain lean mass and long-term training routines, regardless of the eating pattern you choose. He recognizes that protein needs vary for everyone, but if you’re in a caloric deficit and want to preserve muscle mass, aim for 1 g of protein per pound of body weight daily. Here’s a look into his protein regimen and the types of foods he consumes for muscle retention:

| Description    | Details                                                      |
| -------------- | ------------------------------------------------------------ |
| Protein target | 1 g of protein per lb of body weight (2.2 g per kg)          |
| Timing         | Non-specific, distributed strategically throughout the day   |
| Food sources   | Lean meats like fish and beef, protein shakes, legumes, eggs

Attia also recommends incorporating resistance exercise training to preserve and build muscle mass, as it also stimulates MPS, counteracting potential muscle loss during fasting. He emphasizes that muscle preservation isn’t only about your diet but a combined strategy of prioritizing protein intake and consistent resistance training.  

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How genetic testing helps you personalize your fasting regimen

Fasting has been found to be beneficial for metabolic health, inflammation, longevity, and other aspects of well-being. Still, the extent to which individuals can enjoy these health benefits can vary significantly due to various factors, including lifestyle choices, genetic makeup, and individual health conditions.   

What works well for you may not be optimal or safe for someone else. This is where genetic testing becomes useful, playing a valuable role in personalizing your fasting protocol. It provides insights into your genetic predispositions, helping you create a more tailored regimen well-aligned with your genetic makeup.

If you’re interested in how understanding your genetic code can help you personalize your fasting routine to meet your goals, consider taking a comprehensive DNA test with Nucleus. Nucleus is a whole-genome sequencing platform that analyzes nearly 100% of your genome, providing insights into several key areas relevant to fasting, including:

• Metabolic predispositions: It shares insights into your metabolic profile (insulin resistance), enabling you to determine the most suitable fasting window and frequency.  

• Muscle loss risk: It identifies your risk of muscle loss during calorie restriction, helping you better understand how much protein you need, how long you should fast, and how to exercise.

• Inflammatory response: It shares insights into your inflammatory triggers and response to fasting, helping determine if fasting is a suitable strategy for your longevity goals. 

• Obesity predispositions: Reports on your BMI provide insights into your obesity predispositions, identifying risks and benefits associated with different fasting techniques.

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Build a better fasting regimen with genetic insights from Nucleus

Nucleus is the first clinical-grade DNA testing platform that provides in-depth insights into your genetic composition. Unlike commercial testing services such as 23andMe or Ancestry, Nucleus uses advanced whole-genome sequencing to analyze almost 100% of your genome (around 6 billion DNA base pairs). This approach enables you to examine your genetic predispositions and disease risks more closely before making any dietary changes. 

Beyond analyzing your DNA, Nucleus also collects relevant information about your lifestyle and other environmental factors through a detailed questionnaire. This thorough procedure enables the platform to analyze your genetic data in relation to your unique circumstances, resulting in more accurate and personalized health insights that can help tailor your fasting regimen. 

Your test report includes your genetic data along with 20+ reports that show your risk scores for 900+ health conditions. It also offers tailored recommendations for fitness, diet, and other lifestyle categories, helping lower disease risks and boost your health.

Among numerous others, Nucleus’ reports include specific insights related to:

• Type 2 diabetes

• Metabolic diseases

• Cardiovascular health

• Inflammation-related genetic risks

• BMI

• Longevity traits

Although the test findings are presented in simple and clear language for easy understanding, Nucleus partners with SteadyMD to provide you with genetic consultants who can assist in interpreting your results. The platform also transforms your genetic insights into actionable, personalized health recommendations using Nucleus AI, allowing you to take charge of your health immediately.

Nucleus prioritizes data privacy and security, adhering to strict industry practices and regulations. The platform is HIPAA-compliant, while its labs are CLIA-certified and CAP-accredited, demonstrating a commitment to high security and quality standards. 

How to get started with Nucleus

Taking a DNA test with Nucleus is straightforward. All you need is one DNA kit containing everything necessary to collect your sample. Here’s how to get started:

1. Sign up for Nucleus Premium

2. Enter your personal information

3. Place an order for your test kit 

Once your test kit arrives, swab your cheeks to collect the sample, mail the kit back to the lab, and wait for your results. Within 6–8 weeks, the results will be delivered to your online account. 

In addition to your reports, you can also opt-in to receive regular updates and health recommendations based on the latest scientific findings, which will help you ease into your new health and lifestyle modifications.

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 Featured image source: Zacharias Korsalka