How to Boost Autophagy with a 48-Hour Fast

Written By Henry Barnard

This is my 48-hour-fast strategy to boost autophagy. The day before you don’t eat anything have a very low amount of both carbohydrates and proteins (no more than 10 grams for each). Then comes the day without food. The following day, do the same thing with carbohydrates and proteins — no more than 10 grams each.

The average male needs 56 grams of protein for basic metabolic functions. Over the course of the above 3 days, you’ve have supplied only 20 grams of protein when the body has required 168 grams. So the body will have had to scavenge for a minimum of 148 grams of protein — that’s what boosts autophagy.

That you have only digested 20 grams of carbohydrates means that you will stay in ketosis. Exiting ketosis would halt autophagy — the opposite of what you want to have happen.

Use cronometer.com to come up with what you can eat to reduce carbohydrates and proteins to this extent. I rely on plant-based foods high in fat: avocado, walnuts, pecans, brazil nut, and olives.

Caveat: On that third day, given the fact that you have eaten so little carbohydrates and so your glycogen stores are now running very low, you will feel fatigue in your arms and legs. You won’t get to restore the glycogen until the fourth day, but that meal is something to really look forward to.

What this strategy does for you are multiple things. First, on the very first day, given the fact that you have had only 10 grams of carbohydrates and protein, you will get into ketosis and autophagy sooner on that very first day — not just the second food-less day — and second, given the fact that you do the same thing on the third day, just 10 grams of carbohydrates and protein, there will be continued ketosis and autophagy into the final fourth day when you get to eat large amounts of carbohydrates and proteins.

Autophagy is wonderful for the regeneration of youthful cells throughout your whole body, including all your skin cells.

Henry Barnard

I’m a certified nutrition coach through Precision Nutrition, but my education began long before my certification.

In the mid-1990s, I was significantly overweight. During my lunch breaks, I would visit a local bookstore and spend my time browsing nutrition and diet books, searching for an approach that would finally help me lose the weight. That search became a lifelong passion. More than 30 years later, I still study nutrition every day, and my interest has only grown stronger over the last decade.

My coaching philosophy is built on a few simple principles.

No diet pills. I believe lasting weight loss comes from changing habits, not relying on quick fixes.

Gradually increase dietary fiber. Fiber is one of the most powerful tools for managing hunger because it promotes fullness while supporting gut health. As people naturally feel more satisfied, eating well becomes easier.

Eat more whole foods and fewer processed foods. Whole foods retain the fiber and nutrients that help support health and satiety. Building meals around minimally processed foods makes it easier to create eating habits that last.

Use intermittent fasting when appropriate. For many people, intermittent fasting can be an effective strategy to help reduce body fat, improve appetite control, and simplify eating patterns. It isn't the right approach for everyone, but when it fits a person's lifestyle, it can be a valuable tool.

Evaluate level of exercise and quality of sleep.  Simply because these factors have a major impact on any concerted effort to lose weight.  

Focus on 1% improvements. I don't ask clients to transform their lives overnight. Instead, we identify small, realistic changes they can consistently maintain. Those small improvements compound over time.

I tell clients not to judge success after a week or two. Real, sustainable change takes time. As healthy habits accumulate, the results begin to build on one another. Three months of consistent effort can produce remarkable progress—not just on the scale, but in energy, confidence, and overall health.

My goal isn't to put clients on another diet. It's to help them build a way of eating they can enjoy and maintain for the rest of their lives.

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