Breakfast is the most important meal of the day, at least that is what I was taught as a child. But the new trend diet intermittent fasting, makes me question that. By following this lifestyle, you limit your food intake to a certain period of the day, while fasting the rest of time. The length of the intervals between eating and fasting can vary widely, but in most scenarios, people skip breakfast. Is this a trend we should follow?
The reasons for people to choose this diet are plentiful: It is supposed to be healthy, keep us young, and help us lose weight. The often-described positive health effects include a reduced risk of cardio-vascular disease, decreased symptoms of Alzheimer’s, lower blood pressure, and insulin resistance. But are these claims backed up by scientific data?
Different forms of intermittent fasting:
- Aternate-day fasting: You constantly switch between one day with 25 % of the normal calory intake and one day of full calory intake.
- Periodic fasting: You stop eating all together for one or two days of the week. In milder versions fasting days mean eating 25 % of normal calory intake. In extremer versions fasting is extended to one or two weeks, as it is mostly done in therapeutic fasting or for religious reasons.
- Time-restricted eating: You have fixed times during the day when you eat, or fast, for seven days a week. Most common is a regime of 8 h eating and 16 h fasting.
Intermittent fasting vs calory restrictive diet
Intermittent fasting promotes weight loss and improves blood values for markers of cardiovascular health in overweight adults, but so does a calory restrictive diet. For both lifestyle forms, participants of multiple scientific studies lost five to twelve percent of body weight over a period of six weeks. Furthermore, their blood values improved similarly for markers ranging from blood pressure, levels of fasting insulin, LDL cholesterol, and more. Therefore, scientists, who compared the results of eleven scientific studies on both lifestyle forms, concluded that intermittent fasting and a calorie restrictive diet are equally effective to improve body weight and health.
Fasting increases exercise induced fat burning
Performing cardio training before eating breakfast results in up to three times increased fat burning than the same workout would, after breaking the fast. Moreover, when you work out before your first meal, your body continues to burn fat for nine to twenty-four hours afterwards.
For an improved fat metabolism, it is not necessary to fast for sixteen hours, as it is done in the most common form of time-restricted eating. A twelve-hour regime of eating and twelve-hour fasting is sufficient for this effect. Going that long without food results in low blood insulin levels, which is important, as insulin inhibits fat burning during exercise. It does not matter what kind of cardio training you perform, from a brisk walk to a hard run, all results in an improved energy metabolism, when you do it in a fasting state.
Fasting and neurodegenerative disease
Scientists could show that fasting slows down cognitive decline in animal models, which is the process that for instance results in memory loss for patients with Alzheimer’s disease (as described here). However, studies on humans still have to follow, to back up the theory that intermittent fasting can reduce the symptoms of neurodegenerative disease.
Intermittent fasting in praxis
We are so used to our routines that it seems impossible to change our eating habits. But we can train our feeling of hunger, as our body craves food when it is used to getting it. A good starting point for this diet is a vacation, as we usually have breakfast later anyway. The new routine of eating later can then be maintained in everyday life, while not having to go to work hungry.
I know people who have lost weight, just by eating breakfast later and skipping snacks after dinner, they did not change anything about the kind of food they ate. One friend of mine, on the contrary, lost weight when she started to eat breakfast, which she did not do before. That said, everyone’s body is different and there is not one way to lose weight, not one way to be healthy. But, as for any kind of lifestyle, you have to stick to it (as described here). Going back to old routines brings back the cardiovascular health risks and lets the pounds come back in no time.
- Cioffi, I., Evangelista, A., Ponzo, V., Ciccone, G., Soldati, L., Santarpia, L., … & Bo, S. (2018). Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: a systematic review and meta-analysis of randomized controlled trials. Journal of translational medicine, 16(1), 371.
- Vieira, A. F., Costa, R. R., Macedo, R. C. O., Coconcelli, L., & Kruel, L. F. M. (2016). Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis. British Journal of Nutrition, 116(7), 1153-1164.
- Phillips, M. C. (2019). Fasting as a therapy in neurological disease. Nutrients, 11(10), 2501.