Humans have been fasting for millennia, either for religious or spiritual reasons or simply due to lack of food. Today, a new form of fasting called intermittent fasting is increasingly popular among those seeking its anti-aging and health benefits.
Intermittent fasting, or IF, makes fasting an everyday part of life versus something you do once or twice a year. Many people use it successfully for weight loss and inflammation as well as to improve brain function and insulin sensitivity. The promise of increased longevity is another reason people choose to fast regularly.
Different forms of intermittent fasting
Intermittent fasting can be done in a number of ways:
- 5:2 diet — In this plan you eat normally five days per week, and either fast completely, or severely restrict calories (500-600 calories) the other two days.
- Alternate day fasting — This plan includes normal eating for 24 hours and zero, or very low calories (500-600) for the next 24-hour period, alternating every other day. These 24-hour periods typically begin at dinnertime so that in any one day you may miss one or two meals, but not all three.
- 16:8 or 14:10 — Also known as the “eating window plan,” this plan has you eat during an 8- or 10-hour window and fast the remaining 16 or 14 hours of each 24-hour period. For example, you stop eating at 7 p.m and do not eat again until 14 hours later at 9 a.m. the next morning.
Intermittent fasting for weight loss
Restricting caloric intake can lead to weight loss, but intermittent fasting seems to help with weight loss in more ways than that. For one thing, studies show intermittent fasters have better insulin sensitivity and glucose regulation. Among other things, this makes a person crave less sugar and use glucose more efficiently for energy production instead of being stored as fat. Intermittent fasting also causes your body to burn more fat. Because it depletes glycogen, the storage form of glucose, your body switches over to burning stored fat for energy.
Intermittent fasting for brain function
Studies show intermittent fasting can benefit brain function and potentially even stave off Alzheimer’s disease and depression. This is likely due to better glucose and insulin control (Alzheimer’s disease is often called type 3 diabetes), as well as production of ketone bodies for fuel. Ketones provide a ready source of clean-burning fuel for the brain that leave behind fewer free radicals than glucose does. High-fat ketogenic diets have long been used to help prevent seizures.
Intermittent fasting has been shown in trials to reduce blood pressure, triglycerides, LDL cholesterol, and insulin-like growth factor, a hormone that is linked to cancer and diabetes. There is still much to learn about the benefits and pitfalls of intermittent fasting. Fortunately, it is an area of great scientific interest and research is happening at a rapid pace.
Intermittent fasting is not for everyone
Children and teens, pregnant women, people with eating disorders, as well as those with hypoglycemia should not fast. Also, diabetics taking insulin should only attempt this diet under supervision of a doctor.
Women often find less stringent forms of intermittent fasting are more suitable for them. For example, a woman might start by trying a 12:12 eating window plan and potentially lengthen her fasting time gradually, or not, as it suits her.
As always, it is important to understand that there is no one-size-fits-all remedy to any health concern. Contact my office to discuss if intermittent fasting might be right for you.