Of the numerous diets you see talked about online, in books and on TV—all of them intended to help you achieve and maintain your ideal bodyweight—the one I prefer to follow is actually more of a lifestyle than a diet: intermittent fasting (“IF” for short).

Personally, I believe that any number of diets can be effective at helping you manage your weight and achieve a lean physique, as long as you follow the plan as written and stick with it. But that’s the major downfall of most diets: sticking with them for the long-term is not realistic.

That’s why I prefer IF. Again, it’s a lifestyle, not a diet. When I think of a lifestyle, I think of something that’s sustainable. For me, IF has definitely been sustainable—I’ve been doing it for over two years now—and it’s also helped me stay lean while still eating the foods I enjoy (within reason, of course).

So, is IF for you? I can’t answer that question. But I can inform you on exactly what IF is, how it works and what the science says about it. From there, you can decide for yourself if it’s something worth trying.

Intermittent Fasting involves periods of fasting alternated with eating “windows.” One of the most popular and effective IF schemes (not to mention the method I prefer) is a “16/8” plan, where you fast for 16 consecutive hours (time spent sleeping does count) and then consume all of your calories for the day in the following 8 hours.

When you fast is your choice—you can fast from 10PM to 2PM the next day, 8PM to noon, midnight to 4PM, whatever you want. A 16/8 IF plan is intended to be done every day, indefinitely.

Another popular version of IF has you fasting a full 24 hours 1-2 days a week. You’re allowed to eat at any time on the other five or six days, and fairly loosely, depending on your goals. Personally, I don’t prefer this method because of the extended length of the fast – a full 24 hours. I also don’t like the concept of doing IF part time. In my mind, IF is a lifestyle, not a diet you do some days but not others.

This may seem like an obvious point, but I’m mentioning it anyway just to be perfectly clear: fasting means consuming zero calories. No food or calorie-containing beverages are allowed. In fact, I generally recommend avoiding artificially sweetened drinks as well though the science is still inconclusive on this. While fasting, you can drink water, black coffee, and plain green tea. That’s pretty much it.

I often hear people say things like, “When I’m fasting, I’ll sip on some BCAAs or drink coffee with grass-fed butter in it.” If you’re doing this, you’re not staying in a truly fasted state.

Intermittent fasting has become increasingly popular in the last few years. However, I've been interested in its application for weight management for a couple decades. The lab where I did my postdoctoral work at Yale University School of Medicine, along with colleagues at The University of Copenhagen, studied fasting in the early 2000s. My interest in intermittent fasting stems from this research.

There are different theories as to how IF works at the cellular level inside the body to assist in weight management, but it can also be explained more simply: when you shorten the amount of time in which you eat food every day, it’s likely that you won’t be eating as much food as when you leave your feeding window open from the time you wake up until going to bed. So in a very straightforward sense, IF can result in you consuming fewer calories and thus losing weight as a result. After all, calories in versus calories out still matters, even though it’s not the only factor involved in weight management.

The aforementioned weight management benefits make IF very appealing, but consider this practical selling point of fasting: convenience.

Take my schedule, for example. I fast from midnight until 4pm every day. That means I don't have to worry about food or eating until the late afternoon. I have no time wasted on food prep or even sitting down to eat. There’s no need to pack food in Tupperware containers for when I’m out and about, and I don’t have to worry about how to order a “safe” meal from a restaurant.

Not worrying about food until the evening allows me more time to focus on important things like work and carpooling my kids to school and other activities.

There’s also the convenience of not having to play referee every time food is present. With IF, if it’s not your feeding window, you don’t eat the food in question. IF actually gives your brain a break. Once your body knows the pattern, it knows to not even bother you with cravings—at least that’s the way I think of it. This can work well for people who easily give into temptation.

If you’ve never tried IF, or fasting of any kind, you likely have some basic concerns about it. I get questions about fasting all the time—here are some of them, with my responses included:

A: Yes, you’ll get hungry. There’s really no getting around that. But from my experience, it’s not that bad. Stick with IF for a week or so, and there’s a good chance you’ll get used to it and the hunger won’t bother you much. This may sound hard to believe for some of you, but this is a pretty common sentiment for people who have tried IF.

A: You should, yes. Again, anecdotally speaking, people generally claim to have more energy and alertness in a fasted state. Think about how you feel after a big, high-carb meal. Tired and lethargic, right? In the fasted state, you may feel the exact opposite of this.

A: If you keep your protein intake high, you shouldn’t have to worry about losing muscle. Anecdotally, I’ve heard from heavily muscled men that fasting causes them to lose some size, but more normal-sized people should be able to hold onto their lean muscle mass.

That said, you need to consider your goals when choosing an eating style. If your objective is to truly maximize muscle growth, IF would probably not be your best choice. For that individual, I’d recommend a typical bodybuilding-style diet where you're eating every 2-3 waking hours. I’m also not sure that I would recommend IF for a young competitive athlete who trains multiple hours a day for a sport—for example, a high school/college football or basketball player who practices daily and lifts weights in addition to that to maximize strength and muscle building.

A: No, it doesn’t mean that. If you eat unhealthy, you’re likely to be unhealthy. And your physique and performance will suffer over the long term, too. Granted, I often mention that I’m able to eat the foods I love (including donuts and beer) while still staying super lean in part due to IF, but you have to consider a few things. First, I eat donuts and other “cheat” foods in moderation, not every day. Second, the other foods I eat in my feeding window are high-quality sources of protein, carbohydrates and fat. Lastly, I’m very active. I almost never miss a workout (just ask my friends and family!), and when I’m not in the gym I’m still up on my feet and moving around doing something.

My point is, yes, I eat delicious foods like donuts, pizza and ice cream from time to time. But that’s only a very small piece of the pie (pun intended) in my larger scheme of eating clean, staying very active and, of course, fasting 16 hours every day.