Back in my eat-3-meals-plus-snacks-in-between-days, I always seemed to be hungry, or at the very least, fantasizing about my next meal. It seemed that once I began eating on any given day, I simply wanted to keep munching all day. Intermittent fasting is quite liberating because it eradicates all food cravings for the majority of the day. As long as you are consuming adequate nutrients, intermittent fasting is a natural and healthy way of eating. So natural and healthy, in fact, that the body makes it EASY to do by eliminating appetite.
1. PHYSICAL LOSS OF APPETITE
Studies consistently find a loss of appetite in patients on fasting protocols. Consider a fascinating 1990 Swedish study comparing hunger and cravings when people “diet” versus when they “fast.” Two groups of obese patients (one dieting via calorie restriction, the other dieting via fasting) recorded their appetite and cravings over a 3 week treatment period. By the end of the trial, the dieting group experienced very minimal changes in hunger and cravings (they were still hankering for food). The fasting group, however, lost ALL reactivity to food stimuli, with hunger and craving reactions almost zero! The study concluded that hunger and cravings remain constant with calorie restriction, but decrease with fasting.
A more recent 2010 University of Illinois study proposed an “alternate day modified fast” (ADMF) for weight loss, instead of calorie restriction. Patients alternated fasting days of restricted food intake (25% of baseline needs) from 12:00-2:00pm, with ad libidum feeding days. The patients followed a 4 week controlled phase implementing the ADMF, followed by another 4 weeks of ADMF, this time implementing the entire regime themselves. The patients recorded their levels of hunger and satisfaction. While they reported being hungry the first week, hunger decreased by the second week and remained low throughout the rest of the trial. Levels of satisfaction, however, consistently increased! As for weight loss, the patients consistently lost weight even with their ad libitum feeding days when they ate all they wanted, and even when implementing the protocol themselves. Nor did fasting increase their appetite later on: the patients actually ate 5-10% less than their “required” energy levels on their free days. The study concluded that people quickly adapt to fasting, which blunts hunger, increases satisfaction, and sustains weight loss.
2. FUEL CHANGES
Fasting ramps up lipolysis, increasing the amount of fatty acids in the blood stream. This primes the body for the long haul, giving it access to a sustainable energy supply from stored body fat, unlike the limited and wavering carbohydrate stores. A 145 lb person with 18% body fat (a percentage considered “underweight”) has enough stored fat to walk approximately 1000 miles. With the “assurance” of fuel in the fasted state, appetite for food (energy) decreases.
It’s like when people say, “you always had it in you!”…except you did, quite literally.
3. STABILIZED BLOOD SUGAR
Fasting decreases reliance on blood sugar. Sugar stores (glucose in the form of glycogen) are a fleeting thing, determined by your last meal or snack. Your glucose stores are limited, which is why you can’t stock up on carbs for the long haul. Fasting drastically reduces the body’s need for glucose, switching instead to fat. Gone are the hunger signals instigated by low blood sugar a few hours (or less) after your last meal.
4. INCREASED INSULIN SENSITIVITY
With the increase of fatty acids and decrease of glucose comes a lowered need for insulin. Elevated insulin levels increase hunger, while lowered insulin levels reduce appetite.
5. CELLULAR/HORMONAL CHANGES
Fasting also encourages cellular and genetic adaptations which reduce appetite. Cells in the body have inherent circadian rhythms which adapt to temporal feeding patterns. This is why the typical person becomes hungry at breakfast, lunch, and dinner. If you adopt a new consistent pattern of eating, your body’s “hungry” signals adapt to match on a cellular level. (For me, I literally only get hungry around dinner time.)
6. PHYSIOLOGICAL LOSS OF CRAVINGS
Fasting not only reduces actually appetite, it also stops physiological cravings by eradicating feelings of deprivation and allowing satiety. In my calorie counting, dieting days, I fretted nonstop about portion sizes, “servings,” and of course calories. With a fasting regime, I can eat all I want while still maintaining a low body fat percentage.
Studies show a “dieting” mindset increase food cravings. One study analyzed 129 women’s records of food cravings over a one week period. Of the nearly 400 cravings reported, the women dieting featured substantially more cravings than the those not dieting. Since mood, environment, and time between eating weren’t distinguishing factors, the study concluded a dieting mentality alone may instigate food cravings.
Furthermore, these cravings don’t necessarily result from a lack of calories or any actual deficiency. Rather, the restrictive mindset and lack of satiation when “dieting” can instigate feelings of perceived deprivation. A study on dieting individuals found that this perceived deprivation within a dieter’s mind does not actually correlate to actual deprivation or calorie intake, but instead comes from psychological unfulfillment. It concluded that “[dieters] may experience a sense of deprivation not because they are eating less than they need but because they are eating less than they want.”
7. INCREASED WILLPOWER
Intermittent fasting is less taxing on willpower. The brain can only withstand so much temptation within a day. Physcology professor Mark Muraven tested the limits of willpower by presenting students with bowls of radishes and cookies. Some were told to only eat the cookies, others just the radishes. They were then given a puzzle to finish, unaware it was actually impossible (I find this pretty hysterical.) The “radish students” easily gave up, while the “cookie students” worked much longer on the puzzle. Presumably, the students who had “exerted” some of their willpower by ignoring the cookies, had less willpower remaining to work on the puzzle. Mauraven notes that over 200 studies on willpower have found this same idea: “Willpower isn’t just a skill. It’s a muscle, like the muscles in your arms or legs, and it gets tired as it works harder, so there’s less power left over for other things.”
A typical diet overwhelmingly drains willpower. You must constantly restrict meals, refuse snacks, and resist food you want to eat. Since eating is always an option, it’s always a temptation. Intermittent fasting is completely different. Since fasting eradicates appetite and cravings, you no longer drain willpower resources because “eating” isn’t even on your mind. Then when you do eat, you don’t tempt willpower, since you can eat all you wish!
In fact, fasting doesn’t just sustain willpower, it may even increase it! A 2006 series of three willpower studies performed by Australian Researchers Megan Oaten and Ken Cheng found that exhibiting willpower in one area of life (i.e.: dieting) increased willpower in other areas of life (i.e.: TV watching, smoking addictions, etc.)
Even crazier? A 2010 study actually found that fasting helped rats break cocaine addictions! That one kind of seals the deal for me.
8. EASY RESULTS,
A final reason intermittent fasting is incredibly easy to maintain is because it eliminates the hunger, cravings, and guilt of calorie restriction, while still being just as effective. With intermittent fasting, you will never count calories, or weigh and measure food again! You can eat a king’s feast (especially if Paleo), yet lose more weight than you would consciously dieting. You don’t have to even “exercise” for fat burning to take place. As you finally see progress in your goals without pain and deprivation, motivation soars.