Since the 1930’s, animal studies have been telling us that restricting calories improves health and longevity. For many decades, most believed that it was necessary to “starve yourself” to reap the benefits. Recent science has shown us, however, that you can actually trim your waistline, improve your biomarkers of health, and increase your longevity without the pain, suffering, and hunger that comes along with restriction. Intermittent Fasting works, too.
Fasting and feasting keeps us lean largely because it forces the body to metabolize fat for energy more efficiently. And by limiting spikes in blood sugar because there’s no incoming food to digest, your insulin sensitivity can improve dramatically. Another benefit of fasting and feasting: by eating less often, it gives the opportunity for our bodies to repair themselves, without being distracted by needing to digest food. The result is less inflammation, more muscle growth, and of course, more fat mobilization. Studies support that fasting then feasting, or having less frequent meals, doesn’t decrease your metabolism. And eating every few hours, including breakfast, doesn’t increase your metabolism, either. Hunter-gatherer meal patterns, with large dinners and little to eat during the day, seem more natural. That’s why skipping breakfast often comes so easily.
Some studies also show that breakfast boosts hunger throughout the day. I can vouch for that. I tend not to get hungry until I start eating. They’ve found that cortisol is the main culprit. It’s highest in the morning as a normal process of getting you to wake up and prepare you for the day ahead. Often called “circadian cortisol,” the urge to eat in the morning can actually be a response to cortisol flooding our system and not because we are actually hungry. Simply, when you have high levels of cortisol and eat, you’re likely to experience an insulin spike and a decrease in insulin sensitivity. That’s why you might be starving a mere 1-2 hours after breakfast
Not all calories all created equal, the timing of meals can also influence how your body reacts.
When you eat a meal, your body spends a few hours processing that food, burning what it can from what you just consumed. Because it has all of this readily available, easy to burn energy in its blood stream (thanks to the food you ate), your body will choose to use that as energy rather than the fat you have stored. This is especially true if you just consumed carbohydrates/sugar, as your body prefers to burn sugar as energy before any other source.
During the “fasted state,” your body doesn’t have a recently consumed meal to use as energy, so it is more likely to pull from the fat stored in your body, rather than the glucose in your blood stream or glycogen in your muscles/liver.
Burning fat = win.
The same goes for working out in a “fasted” state. Without a ready supply of glucose and glycogen to pull from (which has been depleted over the course of your fasted state, and hasn’t yet been replenished with a pre-workout meal), your body is forced to adapt and pull from the only source of energy available to it: the fat stored in your cells!
Why does this work? Our bodies react to energy consumption (eating food) with insulin production. Essentially, the more sensitive your body is to insulin, the more likely you’ll be to use the food you consume efficiently, which can help lead to weight loss and muscle creation.
Along with that, your body is most sensitive to insulin following a period of fasting.
Your glycogen (a starch stored in your muscles and liver that your body can burn as fuel when necessary) is depleted during sleep (fasting), and will be depleted even further during training, which can further increase insulin sensitivity. This means that a meal immediately following your workout will be stored most efficiently: mostly as glycogen for muscle stores, burned as energy immediately to help with the recovery process, with minimal amounts stored as fat.
Compare this to a regular day (no intermittent fasting). With insulin sensitivity at normal levels, the carbs and foods consumed will see full glycogen stores, enough glucose in the blood stream, and thus be more likely to get stored as fat.
Not only that, but growth hormone is increased during fasted states (bothduring sleep and after a period of fasting). Combine this increased growth hormone secretion, the decrease in insulin production (and thus increase ininsulin sensitivity), and you’re essentially priming your body for muscle growth and fat loss with intermittent fasting.
- 11 AM Work out with heavy strength training in a fasted state.
- 12 PM Immediately consume 1/2 of my calories for the day (a regular whole-food meal, followed by a massive Calorie Bomb Shake.)
- 7 PM Consume the second portion of my calories for the day in a big dinner.
- 8 PM – 12 PM the next day: Fast for 16 hours.
Dangers with Intermittent Fasting in Women
Many women find that with intermittent fasting comes sleeplessness, anxiety, and irregular periods, among a myriad of other symptoms hormone dysregulations. I have also personally experienced metabolic distress as a result of fasting, which is evidenced by my interest in hypocretin neurons. Hypocretin neurons have the ability to incite energetic wakefulness, and to prevent a person from falling asleep, should his body detect a “starved” state. Hypocretin neurons are one way in which intermittent fasting may dysregulate a woman’s system.