You’ve all seen the before and after pictures circulating on the internet. Intermittent Fasting gets results. There’s no arguing that point. But you first must assess your own personal goals before deciding to pursue it as a long-term dietary approach.
There are practical applications to be sure, particularly for sedentary people. Someone can fast during the day, indulge in a late-night dinner without associated health risks, and actually lose some weight. Here were my thoughts about a year ago on STACK.com. It has some health benefits as well, stuff like increased longevity, neuroprotection, increased insulin sensitivity, stronger resistance to stress (I’d argue this), some cool effects on endogenous hormone production, and increased mental clarity (source).
But there are tonnes of guys and girls in the fitness world applying this strategy who shouldn’t be. It’s convenient to follow, and they quickly drop fat, say down to 15% bodyfat, so they praise it to the moon and back. However, most gym buffs want to go lower in bodyfat than that, but they’re already on the bottom end of daily calorie consumption at < 2,000 per day with IF, and so they hit a sticking point eventually. Where do you go from there? 1,500 calories or less? That won’t be fun, and you can bet your remaining lean body mass will be burned through too, sooner than later.
It’s much easier to diet when you’re holding steady at 15% bodyfat at 3,500 calories per day than it is at 2,000! That’s a no brainer. With the former situation, all it takes is incremental drops in calories over weeks and months, while maintaining or increasing energy expenditure in the gym. If you’re eating two meals a day and already exercising consistently, like you would on IF, what’s your plan of attack? Exercise more? Eat even less? Metabolic syndrome, here we come.
My other beef with it is late teens and 20-somethings who somehow think they can bypass the meat and potatoes diet of yesteryear and get ripped and huge with IF. You won’t grow muscle faster by not eating! Sure, you’ll look leaner and can cheat on your diet while doing it, but you won’t split open a shmedium t-shirt anytime soon. Do you think Arnold Schwarzenegger and his cronies skipped meals and trained fasted? No chance. If you’re training as hard as you should be, whether that’s Crossfit, mountaindog training or something else requiring max exertion, you’re going to need some fuel in you. Believe me, I’ve tried it without.
However… (read further if you’re old or a woman)
If you’re an experienced lifter who put his or her time in at the dinner table and in the weight room over decades, not years, you might be fine on IF. You’ve got the lean body mass established and want to size down as you get older for health and longevity. Fair enough. Women, same thing. Women’s bodies better maintain blood sugar levels, even during periods of intense exercise or low carbohydrate intake, and can likely achieve their ideal physique on IF or DH Keifer’s Carb Nite diet, which restricts carbohydrates to one day a week.
If you’re going to ignore my advice and fast anyway, consider the 5:2 version, which allows for five days of regular eating and two days of ultra low calories (these can be your off days from the gym). That just might be the best of both worlds, as you never entirely adjust to a set calorie point and have energy to exercise the way you should. I haven’t put it to practice myself so I’m only speculating at this point though. Maybe some other time!
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