Today I want to tell you about what I used to do, because I rarely lay it all out and a reader recently ask my thoughts on fasting.

For years I fasted every single day, eating within a compressed window. On top of that I did an assisted fast once a month and a 5 day fast every quarter. This wasn't a casual dabble...there is a lot of cancer in my family. I was focused on prevention and the science on fasting and autophagy, which is your cells' way of clearing out their own damaged parts. Research on cancer prevention is also what let me to keto in 2016 since fasting is a lot easier when you're fat adapted and have ketones in your system.

I've since changed how I do things and I want to walk you through why. The research has moved and my own experience taught me something the studies don't put in the abstract.

Let's start with what drew me in, because it was real. Fasting and calorie restriction are among the strongest known triggers of autophagy, the cellular cleanup and recycling process that clears out damaged proteins and worn-out mitochondria. A review in Ageing Research Reviews lays out how fasting flips on these stress-resistance and repair pathways and why researchers have long tied them to healthier aging. The biology isn't hype, it's one of the better reasons to think fasting might do more than take off a few pounds.

Here's what a lot wellness internet skips though. Almost all of the striking cancer and longevity results come from mice and cells, not from long-term trials in people. The same review that gets quoted for the benefits says plainly that we still need randomized human trials to know whether fasting actually prevents the diseases of aging. The rationale is strong but the human proof isn't there yet.

Autophagy itself is more complicated than "cellular cleanup equals anti-cancer." A review in Molecular Cancer describes its dual role. In healthy tissue, autophagy helps keep cancer from starting, but once a tumor already exists, that same recycling can help those cells survive stress. It isn't a simple switch you just want turned up. Much of whether fasting works on existing cancer depends on what type of cancer it is.

Then came the finding that actually moved me. Newer work shows exercise triggers the same autophagy machinery. Research summarized in Current Pathobiology Reports shows physical activity induces autophagy and mitophagy in both animals and people. This cleanup is part of why exercise does us so much good! So the hard training I was already doing wasn't leaving that pathway untouched. I wasn't choosing between autophagy and none, I was getting it from the gym too.

The second reason I stopped fasting as long was more personal and more stubborn: I had a hard time getting my protein in. Squeezing all my food into a short window and losing whole days of protein intake to fasting, made hitting my target nearly impossible. For a woman in the menopausal transition that's not a small problem. A large review in JAMA Network Open found intermittent fasting was linked to loss of fat-free mass, the very muscle we're all fighting to keep. I was potentially trading away muscle I couldn't spare for a prevention benefit that was never proven in people.

So here's where I've landed. I still like a compressed window most days, because it's easy and I feel good on it. But I stopped treating extended fasting as a cancer insurance policy and I stopped letting the clock crowd out my protein. Now, I'm not super strict about a specific eating window. I typically try to have dinner no later than six and end up eating again about 7 or 8 am which is a 13-14 hour fast that still gives plenty of benefit. I train hard, I eat enough and I trust that the same cleanup I was chasing through fasting is happening when I lift and move.

If you've been fasting for prevention and autophagy, I'm not telling you to stop. I'm telling you the picture is more nuanced than the podcasts make it sound and that strength work and enough protein may get you more of what you actually want, without the muscle cost, which is especially important as we age.

If you take one action from this, make it this one: figure out your protein target, because it matters more than your eating window ever will. I built a free protein calculator for exactly this, no email required, and it takes about thirty seconds. It says "for women" to appease the Google god, but it works for men too! Your protein goal is based on ideal body weight, not gender.

.ck-poll-22 tr.ck-poll-option:hover { background-color: #1e1e1e10; }Where do you land on fasting these days?

Hit reply and tell me where you've landed on fasting, whether you still do it, eased off like I did or never started. I read every response and I write back.

Have a great weekend!

P.S. September's High Protein Kitchen went out on Wednesday. Grab it here if you missed it: HPK September 2026 Free Preview.pdf and you'll be on the list for October.