On this month’s Socially Transmitted, KBIA's Rebecca Smith and Najifa Farhat look at what we do and do not know about the practice intermittent fasting.
Farhat spoke with Dr. Benjamin Cook — a family physician with Jefferson City Medical Group and a member of the American Board of Obesity Medicine.
Socially Transmitted is a series where KBIA looks into the science behind online health advice and trends. Have you seen or heard something online that’s left you puzzled?
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Rebecca Smith: I gotta say, Najifa, I’m pretty interested in this one — as you know, I tend to inadvertently fast for many hours because I forget to eat.
So, I’ve been hearing about the idea of fasting for quite a few years now, but admittedly I don’t really know much about it – what exactly is the idea behind intermittent fasting?
Najifa Farhat: Intermittent fasting is when people go without food for a prolonged period — usually anywhere from 16 to 72 hours, and sometimes even longer. Fasting isn’t new. People have practiced it for centuries for religious and cultural purposes. But now, it has gained popularity as a health trend too. I spoke with Dr. Benjamin Cook, a family physician with Jefferson City Medical Group and a member of the American Board of Obesity Medicine. He describes fasting as a kind of reset for the body. Without food coming in, your body starts relying more on stored fat for energy.
Dr Benjamin Cook: So when you're fasting, some of the first things that happen is your body is going to use up the stored glycogen that it has from the food that's been broken down already. And as it does that, it will use up those stores the first couple of six to eight hours. Your body is then going to try to use some of that food that's, or that sugar that's in our liver and the fat tissue to start, breaking that down so it can provide itself its own fuel. As it does that, it tries to clean itself up through some processes called apoptosis or where the body starts to, uh, regulate and almost kind of clean house through different processes throughout the body to help make it run more efficiently.
Rebecca Smith: Well, what does the evidence show — it is safe or effective to restrict food intake in this way?
Najifa Farhat: Dr. Cook says fasting may be helpful for people with certain chronic conditions, including high blood pressure, early-stage diabetes, high insulin levels, metabolic syndrome and even hormonal issues faced by women, such as PCOS.
But he stresses fasting isn’t for everyone. If you have an underlying health condition, it’s important to talk to your doctor before trying it and make sure it’s safe for you.
Rebecca Smith: You need to be medically supervised for that because you want to make sure that a lot of times your body goes through some extreme transformations. It resets your immune system. It lowers blood pressure. It starts to go into a chaotic state. And some people can get what we call the keto flu or feel run down when they fast for too long. If they're not careful, they can get hypoglycemic, pass out. We want people to feel comfortable. And there's ways of fasting appropriately, along with some supplementation with bone broth and things that they need to talk about with their doctor.
"It is one of the biggest concerns that I have for my patients that do fasting, especially if they're only eating one meal a day. We have to make sure that we're supplementing enough protein when you lose weight to help protect that muscle."-- Dr Benjamin Cook
But Dr. Cook says research hasn’t shown that fasting delivers significantly better results than other diets. He says you should still pay attention to what you eat and stay physically active, even when you’re fasting.
Dr Benjamin Cook: It is one of the biggest concerns that I have for my patients that do fasting, especially if they're only eating one meal a day. My goal is to make sure that they're getting enough protein in. We have to make sure that we're supplementing enough protein when you lose weight to help protect that muscle. And that's where I get concerns about long-term fasting especially because we show that fasting, although it has a lot of health benefits, it still isn't superior to regular, calorie-restricted eating when we look at the studies. So short-term fasts are great things, but you need to let your body recover in between those fasts.
Rebecca Smith: So, intermittent fasting isn’t a new idea, but there has been a LOT of focus lately on weight loss — with people taking GLP-1 medications, such as Wegovy or Ozempic. My understanding is that they decrease the desire to eat. So, do we know if it’s safe to use both methods of weight loss at the same time?
Najifa Farhat: Dr. Cook says people taking GLP-1 medications should not consider fasting at all. These medications work by mimicking a natural hormone that helps reduce appetite and makes you feel fuller for longer.
He says adding fasting on top of that may be unnecessary and could work against your health goals.
Dr Benjamin Cook: If people are starting to fast and they're only eating one meal a day with GLP-1s, usually that's a sign that the GLP-1 may not be at the right dose, that maybe too high, or that there is too much calorie restriction going there. What we find is when people calorie restrict too much, they're going to lose muscle mass, feel worse long-term, have saggy skin, and overall don't want them to look gone. I want them to like their best self when they're down to the weight that their goal weight is.
Rebecca Smith: Well, Najifa, thanks so much for looking into this!
