The Problem with Intermittent Fasting


Hello and welcome to the nutrition diva podcast. I'm your host. Monica. Reina. The nutrition world was rocked last week by the publication of a new study which concluded that intermittent fasting is not very effective for weight loss. What's worse? The results suggested that it may exacerbate the loss of lean muscle tissue. Intermittent. Fasting has been a topic of intense public fascination for several years now. I. Give Workshops and lectures and interviews on a wide variety of nutrition topics to a lot of different kinds of audiences, physicians, nutrition, and fitness professionals, senior citizens, college students, parents, and the popular media, and no matter what I'm talking about or who I'm talking to the minute we opened up the floor or the phone lines. We inevitably get questions about intermittent fasting. Is it effective? Is it safe? What does the research say? So it was not surprising that this study caused such a splash despite the breathless headlines though. This latest study didn't actually change what we already knew about intermittent fasting and weight loss and the new finding on muscle loss confirmed a suspicion or concern that many had already raised the allure of. Fasting is totally understandable. The premises that we don't actually have to change what we eat or even how much we eat. We can lose weight simply by changing when we eat it. There are a few different ways that intermittent fasting can be practiced. One of the most popular protocols and the one that was used in this latest study is a restricted eating window instead of spreading your daily meals over the course of twelve or fourteen hours you shorten that eating window to eight or ten hours, for example, instead of eating your breakfast at seven in the morning, your lunch at midday, and then dinner at seven. In the evening you might eat all of your meals between the hours of noon and a PM each day. Now when they tried this in rats, it worked like gangbusters researchers gave the rats a high fat diet, and then they let them eat as much as they wanted not surprisingly this led the rats to gain weight. But when they gave him the same diet and let them eat as much as they want. But only for eight hours a day, they didn't gain weight. In fact, the rats that started out overweight actually lost weight. It seems like the extended fasting period did something to the rats metabolism or maybe their hormones that caused them to either burn more calories or store less fat and if the same were true for humans. That would mean that as long as we kept our mouths shut for twelve to sixteen hours a day, we get all the pizza cheeseburgers, French fries and ice cream we wanted and not gain weight I mean signed me up unfortunately as is so often the case it didn't seem to work quite as well in humans simply restricting your food intake to a shorter window did not seem to change the rate at which humans burn calories or store fat. It did sometimes lead to modest weight loss but this was due to the fact that people following the schedule simply ended up eating fewer calories. No metabolic magic there. In my experience, the benefits of a restricted eating window are purely behavioral. When you limit the number of hours a day that you eat, you often end up eating less which leads to weight loss, and if this turns out to be an easier or more comfortable way for you to limit your food intake than this could be a very successful long term strategy for weight management. I've certainly heard that from many people that I work with. But if you don't eat less, you probably won't lose weight. Now there is just one possible exception. To the extent that there is any metabolic magic in our meal timing, it seems to hinge on eating our calories earlier in the day. So instead of eating between noon and eight PM, you might eat from eight am to four PM and then fast all the way until the next morning this is significantly less popular for obvious reasons, and that's why the authors of this latest study made their eating window from noon to eight pm

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