During a cold winter, which includes moving a little too little and eating a little too much, I’m sure I’m not the only one thinking I could benefit from a few days of healthy eating. Some might even opt for a more radical approach — “fasting diets,” or intermittent fasting. But is fasting a scientifically valid path to health? Can it be an effective way to lose weight — and keep it off?
[See: 10 Unusual Weight-Loss Tips That Actually Work.]
“Intermittent fasting” can mean a lot of different things, but perhaps most popular is the “5:2 approach” or the “eight-hour approach.” The idea is to limit food intake for two days a week (to about 500 calories a day; the 5:2 approach) or to only eat within an eight-hour window most days (e.g., from 10 a.m. to 6 p.m.). Diet gurus hypothesize that these periods of fasting provide metabolic benefits thanks to dropping insulin levels, which leads fatty acids to be released from adipose tissue (or fat stores, which leads fat to be used for energy). Because the fasting protocol is intermittent, overall metabolism should not take a nosedive, though longer-term fasting does lead metabolism to slow.
The Pros
— Not eating usually results in weight loss. I may be stating the obvious, but it must be said: It is almost inevitable that if you eat less you will weigh less. So, not eating much for a day or for even two-thirds of a day is likely to result in weight loss, so long as you don’t simply cram all of your calories into your “feeding window.” When compared to fad diets that focus on more protein or more fat but not necessarily less food overall, intermittent fasting may be better for weight loss or weight management.
— It may be fast. Let’s say you decide to consume only 500 calories next week on Tuesday and Thursday. And, you keep your food intake during the rest of the week to about what it usually is (for healthy men this would be around 2,500 calories per day and for women, 2,000). Having consumed 3,000 to 4,000 fewer calories than usual across the week, you are likely to weigh approximately a pound less than you currently do. If you were to add in some extra exercise (say walking an hour a day on a treadmill), you may weigh up to two pounds less. Across a month, you could even lose up to 10 pounds. By some people’s standards, that’s fairly fast weight loss.
[See: The 10 Best Diets for Fast Weight Loss.]
The Cons
— You may experience the “rebound effect.” Most people naturally compensate when they don’t eat as much as they are used to. So, if you skip breakfast, you’re likely to eat more at lunch. If you don’t eat much on Tuesday, you’re likely to overeat on Wednesday. This “rebound effect” can wipe out any benefit of fasting, unless you are really careful about monitoring what you eat and aren’t upset by being hungry.
— You will be tired. Food is our fuel; it provides us with energy — both physical and cognitive — that helps us get through the day. If you don’t eat (or eat a limited amount), you are likely to be tired and have a difficult time concentrating. And, if you have something important to do on a fasting day or an emergency arises, you may not be in tip-top form to deal with it.
— Fasting sucks. Food is also a source of enjoyment, and depriving yourself of it is likely to leave you cranky and thinking about food more than you usually do. Plenty of research shows it’s quite likely that attempts to fast may result in overeating due to the cognitive preoccupation with food that often results when you try not to eat.
— It’s unlikely to work long term. Like many trends and fad diets, there’s some intuitive appeal to fasting diets. Many of us want a prescription or protocol for weight loss that seems relatively easy and doesn’t require us to entirely give up the foods we love. However, we also don’t want to be hungry, tired and cranky — all of which are likely to occur if we fast. For these reasons, most of us are unlikely to stick to a fasting diet for more than a few weeks or months. And, if we do, it may actually become indicative of disordered eating.
[See: 8 Food Trends Nutrition Experts Pray Will Never Return.]
So, can you fast to lose weight fast? The best answer is probably “maybe.” According to Joseph Dixon, a lipid biochemist, cell biologist and associate professor of nutrition at Rutgers University, New Brunswick, the science just doesn’t support intermittent fasting as weight loss protocol for most of us. Further, research that follows people who have lost weight and kept it off across time has found that the most effective approaches include some calorie restriction and increased physical activity, food and weight monitoring and long-term lifestyle changes that are often anything but fast.
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Should You Try Intermittent Fasting for Weight Loss? originally appeared on usnews.com
