This weight-loss strategy is currently trending, but I’ve seen very mixed results. Here's what you need to know.
In my 15+ years in private practice I donât believe thereâs a one-size-fits-all approach to nutrition and weight loss. What works for one person may not workâor feel goodâfor another. Thatâs why I believe itâs so critical to listen to your body to determine what feels best and is sustainable for you, despite how popular an approach may be, from juice cleanses and detoxes to âcavemanâ versus vegan diets.
Regarding one strategy thatâs currently trending, intermittent fasting, Iâve seen very mixed results. Many men, particularly those who struggle with excess weight and conditions like diabetes or metabolic syndrome, have reported positive results with this semi-fasting approach. But for many women Iâve counseled, any type of fastingâwhether it be overnight for 16 hours every night, or capping calories at 500 two days a weekâhas seriously backfired. If youâre thinking of giving it a try, here are four potential unwanted effects to consider.
Limiting food intake to just eight hours each day or severely restricting calories a few days a week are two popular fasting approaches. Iâve seen both lead to intense cravings, preoccupation with food, and rebound binge eating, particularly for women. Some who attempted to cut off eating after 4pm (with the intention of eating again at 8am) have told me that after hours of lingering thoughts about food, or watching other family members eat, they just couldnât take it anymore, and wound up raiding the kitchen and eating far more than they would have on a typical night. Others, who attempt to eat no more than 500 calories a day two non-consecutive days each week, often begin daydreaming on fasting days about what they can eat on nonfasting days, and end up eating decadent goodies more often, like baked goods, pizza, chips, and ice cream. The lesson: even if this tactic has worked miracles for a friend, co-worker, or family member, if it leaves you in a food frenzy, itâs not the best approach for you.
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Iâve tried intermittent fasting myself, and like clients and others Iâve talked to, it interfered with my ability to fall asleep and stay asleep. This effect can not only wreak havoc with daytime energy, but a plethora of studies have shown that sleep length and quality are strongly associated with weight control. Too little sleep has been shown to increase hunger, up cravings for sweet and fatty foods, reduce the desire to eat healthy foods like veggies, and trigger excessive eating overall and weight gain (for more about the importance of sleep, check out my previous post 5 Healthy Habits That Regulate Appetite). For these reasons, I donât believe that fasting is an optimal strategy for many people. In fact, some clients have told me they got out of bed at 3am after waking up, and you guessed it, wound up either eating, drinking alcohol, or both, in order to fall asleepânot a good recipe for weight loss or wellness.
As a nutritionist, one of my biggest pet peeves with fasting is that Iâve seen it compromise overall nutrition by limiting the intake of veggies, fruit, even lean protein and healthy fats, which are strongly tied to keeping metabolism revved, boosting satiety, and reducing inflammationâall critical for weight control. I think this is especially the case when people become focused on calorie counts rather than food quality (for my take on why a calories-in-versus-calories-out philosophy is outdated, check out my previous post Why Calorie Counts Are Wrong). If you do decide to try intermittent fasting, or even a modified version, make every morsel count by sticking with naturally nutrient rich whole and fresh foods rather than processed âdietâ products.
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Unfortunately, fasting doesnât trigger your body to break down only your fat reserves. While that would make weight loss so much easier, metabolism is a bit more complex. Your body burns a combination of fat and carbohydrate and after about six hours or so, when carbohydrates arenât being consumed and your bodyâs âback upâ stores in your liver have been depleted, you begin to convert some lean tissue into carbohydrate. The ratio of how much fat to muscle you lose may vary depending on your body composition, protein intake, and activity level, but again, this is where Iâve seen women and men experience different results. Research shows that in postmenopausal women, a higher protein intake is needed in order to lose less muscle mass (not offset the effect completely), but many women tell me that when they fast they crave carbs, which may lead to a loss of muscle while maintaining body fatâthe opposite of their intended goal. Bottom line: again, think through what feels good and in sync with your bodyâs needs, and remember, sustainability is key!
Cynthia SassÂ is a nutritionist and registered dietitian with masterâs degrees in both nutrition science and public health. Frequently seen onÂ national TV, sheâs Healthâs contributing nutrition editor, and privately counselsÂ clientsÂ in New York, Los Angeles, and long distance. Cynthia is currently the sports nutrition consultant to the New York Rangers NHL team and the Tampa Bay Rays MLB team, and is board certified as a specialist in sports dietetics. Her latest New York Times best seller isÂ S.A.S.S! Yourself Slim: Conquer Cravings, Drop Pounds and Lose Inches. Connect with Cynthia onÂ Facebook,Â TwitterÂ andÂ Pinterest.