We don't fast enough and if we did, we would be better off in many ways. Fasting is a positive practice and even has benefits beyond the physical. The hardest thing about learning to eat better is learning to be a little bit hungry. Fasting on a regular basis can train us to do this. Fasting of course goes way back in many traditional religious cultures as ways to draw closer to God or the gods and to purify the soul of idols. Some of the age-old religious truth carries over into our approach to food and it definitely helps us to appreciate food more if we learn to limit it.
More is not always better. In economics, marginal utility is a principle that states the benefit we get from one more unit of a given item. I've used the example of a slice of pizza before. If we get one slice of pizza only, it tastes incredible and we really enjoy it tremendously. If we get 10 pieces of pizza, this is not 10 times better is it? No way, and so the marginal utility of a food like pizza decreases as well as eat more of it. The same goes for pretty much every type of food- 4 cups of coffee versus 1, 3 salads versus 1, and so on. By limiting things, we appreciate them more.
Eating less is obviously hard. We have discussed many tricks of the trade, like food logs, drinking more water, eating more fiber, decreasing portion sizes, and combining nutrient groups like protein and fat with other types of nutrients, in order to feel more full. Fasting can also help us eat less because it can train us to go without. I normally fast a little on Friday, 16-20 hours starting on Thursday evening. There's a point on Friday mid-morning where I usually think "I'm not sure if I can do this much longer" but once I get over that hill, the rest of the day is pretty easy. I do this for health reasons, but also because it has a connection on Friday to traditional Christian practice, and so its meaningful for this reason to me. I've also found that a weekly fast has increased my self-discipline in other areas of life as well, which is a nice side benefit.
I recommend fasting also because it could elevate your insulin sensitivity, which as we have discussed is a major plague in our society. Insulin sensitivity is crucial for weight control and aging well. I know clients and friends who swear by fasting and what it did for their metabolism, though I don't think it would work for everyone. When you're in a brief period of fasting, less than 24 hours, your metabolism normally actually increases, with hormones like growth hormone and testosterone increasing short-term. It is as if the body is stimulated to rev things up to make up for the fact that it isn't getting any food. A regular short-term fasted states promote a higher sensitivity to insulin over the rest of the week, which could make a big difference in how your body handles food over time. Be careful though, because over a long term period of fasting, more than a day or two, your metabolism would likely slow down like someone who was starving, because your brain and body would shift into a survival mode. This would make it difficult to lose weight and be counter-productive, so stick with short term fasting. Long-term starvation diets always lead to yoyo weight gain and loss so I don't recommend them.
I love the KISS (Keep it Short & Simple Principle) in just about everything, and fasting is no exception. Another unbeatable thing about fasting is it's simplicity. All you have to do is not eat for a period. There are no long and expensive programs, books, or shakes. There are no "secret methods" and no gurus to learn from. And you actually save money because you're eating less right off the bat!
If you decide to fast, keep in mind, when you come off the fast you will be extra hungry and may overeat. I did this when I first started fasting, but now am aware of it more. Just remember it will be easy when you come off a fast to have something healthy in mind and prepared to eat, so you don't go for the easiest junk food in sight.
And as always, talk to your doctor first, before you start a new fasting program, particularly if you are diabetic.