Why is fasting is popular for weight loss?
So flash back to my college days. Here I was, awkward in my body, feeling anything but sexy and thinking that all of my problems could disappear easy peasy if I could snap my fingers and become a skinny girl. I just needed to figure out how to lose weight for long enough and in a consistent enough way to reach my goals. I was stuck in this body that I didn’t feel should be mine. And fasting seemed like the perfect answer.
I’ve tried a couple of approaches to fasting. In the first version, I would go a few days without eating anything. Sure, I would feel weak and light-headed and miserable. But if I could just shed a few pounds quickly, then I could lose the rest with responsible dieting. And fasting would be a great jump start to help get me on my way.
The second approach was daytime fasting. I wouldn’t eat at all during the day to save my calories for dinner. And yes, I would have a somewhat larger dinner. But eating one large meal would still mean consuming fewer calories over the course of the day than eating 3, more reasonably sized meals.
I would lose weight. Fasting just never helped the weight to stay off.
Science and Fasting
The month-long celebration of Ramadan has provided researchers with very helpful information about the act of fasting and its impact on weight. During the month, observers abstain from eating and drinking until sunset on a daily basis. Fasting is then followed by compensatory overeating to regain energy stores. This is often marked by weight gain and high levels of plasma lipids without an increase in total calories. 
So what is going on here? Why does fasting lead to weight gain when overall food intake is decreased?
It really comes down to something as simple as hormonal interaction. You have hormones in your body that tell you when you’re hungry when you’re full, and how much fat your body should store. Much of your extra weight is the fault of a malfunction in this hormonal system. All these hormones work together, and if one of them isn’t working correctly, none of them will.
As you might imagine, not eating all day increases the hunger hormone to very high levels. This puts your body into starvation mode. And when your body is starving, it wants to conserve energy. Resuming eating will signal your hormone to go into fat storing mode. And this makes it possible for everything you eat to be turned directly into fat. Ever have a friend who complains that she don’t eat anything but is gaining weight? Now maybe you’ll believe her.
The bottom line about fasting for weight loss
If you have an event in a few days and your dress feels a little tight, fasting may help it fit perfectly by the day of the event. Just plan to gain all the weight back, with possibly a little extra by the time you go back to normal eating. I personally wouldn’t recommend this approach. But if your goal is to lose quick, temporary weight, fasting could be effective. But if you are looking at fasting because you want to feel confident, sexy and healthy on a daily basis, fasting, in my opinion, isn’t the way to go.
I know that you might be nervous to consume calories earlier in the day for fear that you’ll overeat in the evening. Evening tends to be a time when diets can unravel and a day of discipline can evolve into a nighttime binge. And last week I talked about preparing for such obstacles in your weight loss plan. But what I say next may shock you.
Even if you take in extra food through a nighttime binge, it is better for your waistline to eat consistently throughout the day than to daytime fast. Your overall caloric intake may be higher than if you didn’t eat in the morning. But you probably won’t store quite as much fat. And since your hunger hormones will be more in balance, you might not binge to such an extreme.
Fasting is tempting as a quick fix for extra pounds. I get it and I’ve totally been there. It is also an unavoidable part of many religious rituals and I’m certainly not recommending deserting your religion But I hope you now see that fasting probably won’t lead you to the results you’re really looking for weight loss. Eating early in the day (preferably within a half hour of waking) is a wonderful way to establish proper hunger and fat storing signals for the day. And a more moderate diet, filled with good quality protein, fats, and carbohydrates will be a more effective weight loss journey for the long term.
- Han, JM, Kim, HG, Lee, JS, Choi, MK, Kim, YA & Son, CG. (2014). Repeated sense of hunger leads to the development of visceral obesity and metabolic syndrome in a mouse model. PLoS one. Vol 9(5). 0098276.