Does fasting offer any proven benefits? Roshan Kore has some answers
Fasting has been recognised for its many health benefits dating back to Hippocrates. These benefits extend to everything from better weight management, improved cardiovascular health, healthier blood composition, and better cell recycling, among many others.
When it comes to diet, the questions that concern scientists are no longer simply, ‘What should we eat?’ and ‘How much should we eat?’ Now, it is when we should eat and whether we should eat at all — at least for certain periods of time.
Fasting improves body composition This happens primarily through its actions on hormones and fat metabolism.
It promotes greater satiety With fasting, leptin levels drop initially, but as you lose weight, you decrease leptin resistance. Improved responsiveness to leptin signals increases how full you feel.
Fasting boosts metabolism Leptin, though known primarily as the ‘satiety’ hormone, also increases thyroid hormone production. Improved leptin sensitivity increases the rate of metabolism if you have a sluggish thyroid.
Fasting supports fat loss and ketosis. Ketosis, or the fat-burning state, is reached either by fasting or eating a diet centred on healthy fats. Ketosis helps you burn through your fat reserves. A study has found that fasting significantly boosted fat metabolism in humans.
It encourages better insulin sensitivity Fasting causes the body to secrete less insulin because you’re not giving yourself steady doses of sugar. Lower levels of this hormone lead to increased sensitivity in those with insulin resistance.
Improves cardiovascular health Fasting improves cardiovascular function, blood composition, and blood pressure.
It lowers blood pressure. While fasting, many people develop lower blood pressure, primarily during the first week of a fast. It might not be fasting itself that decreases blood pressure, but rather a significantly lower salt intake and increased loss of salt through the urine.
It decreases blood sugar In just the first few days of fasting, blood sugar drops over 30%, a significant perk to anyone with hyperglycaemia.
It improves blood triglycerides and promotes heart health Blood triglycerides decrease during the fasting state. Having fatty blood increases your risk of developing narrowed arteries and cardiovascular problems.
It may slow aging and enhance longevity The effects of fasting appear to lead to a healthier, longer lifespan.
It decreases inflammation and increases resistance to oxidative stress Foregoing a few meals prevents food-related inflammation before it even starts. Another way that fasting decreases inflammation is through better hormone balance. Several studies have found lower insulin levels and improved insulin sensitivity decrease oxidative stress caused by free radicals.
Total fasting diets [with zero calorie consumption] are not a good idea for a couple of reasons. You’re more likely to start losing lean body mass. You will get, potentially, big fluctuations in fatty acids, which could lead to insulin resistance. And you’re going to get increased hunger. Also it is difficult to do them.
When you dramatically reduce your calorie intake, you will lose weight. But it can also cause all kinds of health problems, including muscle loss. Further, when you start fasting, your body goes into conservation mode, burning calories more slowly.
Keep in mind that the initial weight lost on a fast is primarily fluid or ‘water weight’, not fat. And when you go back to eating, any lost weight usually gets a return ticket back.
Not only do most people regain weight lost on a fast, they tend to add a few extra pounds because a slower metabolism makes it easier to gain weight. Worse, the weight that is regained is likely to be all fat—lost muscle has to be added back at the gym.
Roshan Kore is Senior Dietitian, Narayana Health - SRCC Children's Hospital