I remember a couple of years ago when I wrote my first article about skipping breakfast. People called me radical, crazy, extreme. Magazines told me I could write whatever I wanted for an article, except suggesting that someone skip breakfast. And a friend of mine advised me, for the sake of my business, to forgo pushing the “no breakfast thing” because it was just too out there. You needed to break-the-fast, as I was told, it was just common sense.
The climate of popular diet suggestions has since changed. No longer is it taboo to skip breakfast, or even lunch. Some people go so far as to recommend skipping dinner or refraining from eating for an entire day. Not only has fasting become trendy, it’s also been upgraded to intermittent fasting (IF), and early adherents claimed everything from lean muscular gains to achieving a ripped physique. A couple of years ago, intermittent fasting was an idea on the fringe. Today, IF—along with skipping breakfast—is on the rise.
In 1988, a study published in the Journal of Clinical Investigation showed that without eating for 24 to 48 hours, humans start to produce regular spikes of growth hormone (GH), much as we do during a normal sleep cycle and upon waking.(1) It seems that eating disrupts the rhythm and intensity of GH release. These GH pulses—which occur about every three hours in overlapping frequency patterns—were thought to increase fat loss, retain muscle mass, and even to allow the building of lean muscle while losing body fat. But no one had, at the time, conducted a valid experiment to test the idea.
The proposition is tempting. Stop eating and get massive repetitive spikes of growth hormone, with its anabolic, fat-burning properties. Why wouldn’t you get lean and ripped, add a few pounds of muscle, and increase your strength?
There’s one problem with this line of reasoning: Maybe GH will help burn fat, but how can it create an anabolic environment without raw material, without excess fuel? You’re fasting. There’s no direct storage mechanism for protein in the body, so no way to call on reserves for building new muscle.
Nobody seemed to stop to consider this question, and the fasts started growing from skipping breakfast, to breakfast and lunch, until finally IF bowed to the whim of the singular study and 24- to 48-hour fasting became commonplace.
Science Optimizes Everything
I don’t haphazardly strip breakfast from someone’s diet. It’s something I reserve for those losing body fat while maintaining or even gaining muscle—most notably, for those embarking on the road to a bodybuilding competition. Numerous studies have actually shown that skipping breakfast and moving your calories to the end of the day (rather than the beginning) can accelerate fat loss and spare muscle mass while dieting.(2–6)
If you look at the hormonal happenings first thing upon waking, it only makes sense: Cortisol levels and ghrelin levels are both elevated upon waking and insulin levels are extremely low. High cortisol levels working in the absence of insulin actually mobilize body fat; in the presence of insulin, it causes fat accumulation. Clearly, don’t eat carbs first thing in the morning if you’re trying to lose body fat.
In addition, the elevated ghrelin levels cause a spike in GH release within a couple of hours of waking, which can help accelerate fat loss and preserve muscle mass. Extending the fast past breakfast can be advantageous, particularly when shredding down.
Everything Useful Has Limits
If skipping breakfast works so well, maybe skipping a few more meals will work better. It’s the gym rats anthem: More is better. Maybe there is something to skipping a day or two worth of food. Lucky for us, this is one arena that science has explored, and the results help us define not only the optimum time of day to fast—during sleep and in the morning—but also the maximum length of time.
Go beyond this fasting time limit and suffer a state of potent anti-growth. It’s been demonstrated that fasting upward of 24 hours or more actually turns the body anti- anabolic. Fasting prevents growth.
Fasting for more than 12 hours shuts down the mTOR pathway of tissue growth. Now recognized as a critical component of skeletal muscle growth, the mTOR pathway, once shut down, kills your ability to add new muscle mass.(7) And if you happen to train during this time (in the middle of a 24-hour or longer fast) even insulin—arguably king of the anabolic hormones—loses the power to stop the muscle protein breakdown that occurs with training.(8–9) Not to mention, with mTOR shut down, catabolic processes run rampant, destroying hard-earned, quality mass.(10)
There’s even evidence from animal models that fasting for periods longer than 12 to 14 hours increases white adipose tissue’s ability and affinity for storing fat. In other words, fasting partitions nutrients away from fuel use and into storage, increasing the chance of metabolic fallout and fattening up.
From The Ashes
All is not lost. The latest research doesn’t exclude fasting as a useful practice; it helps us to use fasting appropriately and not go overboard. I know from the research and from working with countless athletes that skipping breakfast accelerates fat loss and preserves muscle mass. The scientific exploration of fasting tells us the best time to break the fast, or the longest period of time we can push it, so to speak, which is 12 to 14 hours before we shut down the ability to increase muscle mass.
So we can see that how long you can go without food each day depends on the last time you ate the night before. Eat immediately before going to bed, sleep eight hours, and you can hold off eating the following morning for another four to six hours. Stop eating at 7 p.m., hit the sack at 10 p.m., and then sleep eight hours, you’ve got only an hour to spare before eating, but you’ve screwed up the early-morning, fat-burning window mentioned above.
Advantages Only, Please
IF is in jeopardy of becoming a fad because as with all new concepts or ideas, recommendations outpace science. By the time science catches up, each camp must stick to its guns, defending an indefensible position.
The real tragedy with fads is that since no one uses the research to recant, refine, then relaunch their procedure, the entire practice fades into disfavor and the useful components go as well. We can use fasting to our advantage and get accelerated fat loss, preserved lean tissue, and the sensation of a heartier meal or two later in the day by listening to what the intersection of science and observation have to tell us: that we should hold off breaking the fast when we wake for at least a couple of hours.
REFERENCES: 1. K.Y. Ho et al., J Clin Invest., 81(4):968–75, 1988. 2. N.L. Keim et al., J Nutr., 127(1):75–82, 1997. 3. E. Hirsh et al., Chronobiologia, 2(suppl 1): 31–32, 1975. 4. H. Jacobs et al., Chronobiologia, 2(suppl 1): 33, 1975. 5. F. Hal- berg, J Nutr., 119(3):333–43, Review, 1989. 6. S. Sensi and F. Capani, Chronobiol Int., 4(2):251–61, 1987. 7. M.J. Drummond et al., J Physiol., 587(Pt 7):1535–46, 2009. 8. K. Inoki et al., Nat Cell Biol., 4(9):648–57, 2002. 9. A.C. Gingras et al., Genes Dev., 12(4):502–13, 1998. 10. N. Shimizu et al., Cell Metab., 13(2):170–82, 2011.