This study shows the benefit of intermittent fasting in providing increased weight loss. Participants in the study arm ate their food over an eight-hour period from 7 am to 3 pm and they lost 5 pounds more over 14 weeks than the control group. Achieving that weight loss in just over three months is a tremendous accomplishment. On average, Americans eat over a period of almost 15 hours. Some eat the whole time they are awake.
Let’s think about the reasons intermittent fasting works better. Part of the explanation lies in human biology and evolution. During most of modern man’s existence, we were hunter-gatherers. Food was not always available as it is for us. When a large animal was killed, food was abundant, but that might be followed by hours or days before the next large meal. This pattern was especially important for the young before and after birth.
Our genes are still adapted to help us survive and grow depending on how much food is available. There is a master metabolic genetic switch called the mechanistic target of rapamycin (mTOR) that is central to coordinating fetal growth with food supply. When food is plentiful, mTOR is maximally switched on to activate the many genes that coordinate and promote growth. mTOR activation also favors increased fat deposition. When there is no food, mTOR is switched off and another master genetic switch called AMPK is switched on. These two switches are related. When one is switched on, the other is switched off.
mTOR is about growth. AMPK is about survival. When there is no food, the fetus and child need energy to keep the heart and brain going to support life. Switching on AMPK pulls calories from muscle and fat stores to provide that energy. This system is central to producing healthy, strong, young adults who can have children and provide for them. Once that is accomplished, when we are no longer growing, switching on mTOR and switching off AMPK makes us age faster and develop chronic diseases sooner. Producing growth in the cardiovascular system in adults makes the heart bigger and the arteries thicker. That raises the blood pressure and causes heart attack and heart failure. Genes that are essential in early life kill us later.
Eating switches on mTOR. Not eating switches it off and activates AMPK. That is why intermittent fasting is the preferred eating pattern that provides health benefits even beyond weight loss. The medications that prolong life and delay chronic illness more than expected like metformin and empagliflozin also switch on AMPK and switch off mTOR. These are the critical switches that govern chronic illness and aging.
I’ve been intermittent fasting since around 2012. As paleo, low carb and now ketoish I’m just not hungry until after 11 am. (If then). It keeps my weight stable. I forget to eat often. I was never much of a breakfast eater anyway. If I’m not hungry—I don’t eat. When I was younger I was bulimic and had no idea how to eat normal. I quit the behavior but it still took a couple of years to get my head around a normal eating pattern-for me. I found it with a low carb-clean food lifestyle. Giving up wheat and grains explained some physical and mood problems I had always had. Anxiety and low grade depression. I stay away from seed oils too. It works. I have many pre diabetic relatives and they just don’t get it.
Interesting study, Bill. I’ve always found that I lose weight dependably when I restrict eating to times that I feel actual hunger. This means I will sometimes skip lunch or dinner, just because I don’t have an appetite. I tend to gain weight when in social groups or events, as there is always food around and set meal times that you often can’t skip.