Over the years, I've done several interviews with Dave Asprey, a Silicon Valley entrepreneur, founder and CEO of bulletproof.com, including one in which we discuss how ketones may be useful against COVID-19. Here, we discuss his latest book, "Fast This Way: Burn Fat, Heal Inflammation, and Eat Like the High-Performing Human You Were Meant to Be."
As the name implies, the book is about fasting and all the magnificent health benefits it provides. Is it for everyone? No, and he will be the first to admit that. But it can benefit most of us, certainly, those of us who are either overweight or obese. In his book, Asprey tells his own journey into fasting and what he's learned along the way.
"The word fasting is associated with pain, and I wanted to teach people some hacks for fasting," Asprey says. "I also put a whole chapter in for women, because fasting doesn't work for everyone and there is no one best kind of fasting. The evidence seems pretty clear that fasting the same way every day or every week is probably also not the best strategy.
So, how do you make it so you can fast without pain when you have stuff to do? And how do you make it so you fast with all of the emotions of fasting when you want to really dig deep and do the meditation, personal development side of fasting? Sorting through all that hasn't been done in a book, so that's why I wrote it."
Breaking the Starvation Myth
As noted by Asprey, a common concern is that fasting will put your body into starvation mode, thereby actually preventing fat loss. This is a persistent belief, but it's not true. That said, some strategies will indeed activate starvation mode, such as when you're eating a low-calorie diet for months on end. Asprey tells a personal story that encapsulates this dilemma:
"On my journey of losing 100 pounds, I was doing what everyone said would work. I went to the gym an hour and a half a day, six days a week, halfway tough cardio until I could max out all but two machines, and I would do 45 minutes on the treadmill at a 15-degree angle wearing a backpack — really just pushing it.
And, I went on a low-fat, low-calorie diet. At the end of 18 months, I'm sitting at a Carl's Jr. with friends. I'm eating the chicken salad with no chicken and no dressing and my friends are eating double western bacon cheeseburgers. I looked around and I'm like, 'I exercise more than all my friends and I eat less than all my friends, even though I'm taller than they are. Maybe I'm just eating too much lettuce.'
To have a 46-inch waist after that much exercise, low-calorie dieting and all the suffering and intense hunger … My god, the sense of personal failure that comes with that, it's one thing that holds people back and makes us stay heavy.
What's going on there is there is a hunger set point that is caused by ghrelin, one of the hunger hormones. It's a precursor to leptin. Research has shown that when you lose weight using a low-calorie diet or excessive exercise — and I was doing both — your hunger set point will remain your fat set point, and it will always do that.
The thing that turns your set point for hunger to your actual weight instead of to your fat weight is ketones. So, if you were to fast for a couple days or use the fasting hacks that I talk about in the book — there are three fasting hacks to turn off hunger, and two of them are going to help get your ketones up — even just one dose will reset your hunger levels."
As explained by Asprey, yo-yo weight loss and weight gain occurs because you're on the wrong diet. Key dietary principles for losing the excess weight and keeping it off include:
- Getting at least half or more of your daily calories from healthy fats
- Eating the right type and amount of protein
- Avoiding inflammatory foods, including inflammatory vegetables (culprits include lectins and oxalic acid, for example)
- Having periods of time when you fast (abstain from food)
Key Benefits of Fasting
So, what are the main benefits of fasting? Is it just the ease of weight loss? As explained by Asprey, there are many other health benefits to fasting beside the fact that stubborn weight will fall off. Importantly, the primary benefit of fasting is that it makes your body better at making energy.
This in turn has several benefits, one of which is improved blood sugar regulation, which will allow you to stave off insulin resistance and metabolic dysfunction and all the diseases of aging associated with that. As noted by Asprey, if you can avoid cardiovascular disease, cancer, diabetes and Alzheimer's disease, you're probably going to live longer, as these are the primary killers.
Fasting is also antiaging because it improves autophagy in your mitochondria and cells. Autophagy is a natural process that cleanses and detoxifies your mitochondria and cells. By breaking down old, damaged organelles, fresh, new ones can be made to replace them. And, with healthy, new mitochondria, your body can make more energy, more efficiently.
"That's an unappreciated side of fasting," Asprey says. "High-intensity interval training will do something similar, but when you combine that with fasting, your body is like, 'Get rid of that old stuff.' It's kind of like a snake shedding its skin. It's that autophagy process that is a really big deal."