Intermittent Fasting: Silver Bullet or Snake Oil?
Do you want to be a lean, mean, sex machine?Increased energy! Better, more restful sleep! Higher testosterone! Sex drive through the roof! Watch fat melt off in weeks as you preserve hard earned lean muscle! All with this one trick…..
We have all seen this ad. Usually accompanied by a quick fix supplement or sales pitch. While those ads are usually pretty easy to spot a mile away it is harder to differentiate the good from the bad when it comes to diet trends. Atkins, Keto, Paleo, Zone, South Beach. Each of these has legions of followers that swear by their efficacy and proclaim each to be the only way to eat. All have their merits and there is a way to show why each works. What about intermittent fasting or IF?
Intermittent Fasting: The Next Big New (Old) ThingIntermittent fasting has become a hot topic in the fitness world and amongst people of all walks of life as a way to lose fat. The basic definition of IF is that there is a period of fasting followed by a period of feasting. My initial exposure to IF was in reading about it in the calorie restriction community who used 24-48 hour fasting periods to severely restrict caloric intake. Their goal was not a fitness or aesthetic one, they were operating on the assumption that caloric restriction will lead to a longer and healthier lifespan. I have no idea if this is scientifically or anecdotally corroborated.
The IF community that I am much more interested in is within the fitness community, usually done to enhance body composition. This method of IF is usually done by restricting the “feasting” window to a period of 8-12 hours depending on goals. The idea being that the body will burn calories at a more efficient rate if more of the early waking hours are lived fasted. So, you might have your last meal at 8pm Monday night. You are focused on maximum fat loss so your fasting window will be 16 hours long. That means you might wake up at 6am and not eat your first meal until noon on Tuesday. You would eat meals at predetermined times throughout the day having your final meal at 8pm Tuesday night and start your “fast” once again.
Get Big and Stay LeanThere are different modifiers for the individual diets. The most familiar protocol to me is one in which the fast is broken with a meal composed of protein and fats and carbs are added in timed around workouts and in the night time window. The thought behind this is that nighttime carbs will supply your body with the glycogen needed to operate in the morning fasted period when most of your activity is based around your work (which may or may not be sedentary). The exception to the fasting window in some of these diets tends to be adding mct oil or butter to your morning coffee (I know, I don’t consider a 500cal cup of coffee as still fasting but that’s another post).
When resistance training is planned some fast acting carbohydrates such as berries or fruit juice (for the “primal” diets) or simple sugars like dextrose (for those not concerned with processed sugars) will be added immediately before and possibly during training. The post-training window will consist of protein and a mix of simple and complex carbs. This training window can be a little more complex depending on time of day that training is proposed and how it works with nutrient timing but that is diet dependent.
But Jeb, Does It Work?I know what you are asking yourself. Does intermittent fasting actually work? The answer is, yes, sort of. I must state here that I have used an IF protocol to lose fat and it was very effective. Part of the effectiveness for me, however, was just the diminished time I had to eat. There have been times in my life that I have to be up at 5am with clients and not home until after 9pm. If I started eating when I woke up I would hit my caloric needs for the day by 2pm. So, for me, IF was the way to go. I don’t like breakfast food, I like to eat right before bed, and I train in the mid afternoon. I can get my first meal in somewhere around noon, have a little pre-workout snack, then a couple of meals after my workout. So it works, but not really for any other reason than any other diet works: caloric restriction. (If you would like to study this further Alan Aragon did a survey of a decade’s worth of studies and found no difference in body composition between IF and other forms of diet)
We know, then, that for fat loss IF works. What, if any, drawbacks does IF have? For me, and this is a biggie, muscle gain is tough. Simply put, limiting your caloric window to 8 hours means that you will have to either eat a ton of food at each meal or resort to more calorically dense choices than is healthy, i.e. junk food. If it’s just mass gain that you’re after than by all means slam some McD’s a few times a day but don’t be surprised when a lot of fat comes with a little muscle. The other drawback is the act of fasting at all. Some people just can not go long periods without food and develop the dreaded “hanger” and rebound so hard that they end up eating more. My wife is one. Her IF experiment was short lived and if it had been longer I might be short-lived.
All in all, if it’s fat loss you are after, you can stand to go long periods without eating, and enjoy eating the majority of your meals at night then give it a try. Just be sure to set your calories to match your goals and not be under the impression that the fasting itself is the reason for fat loss on IF.