Meal breaks or so-called interval fasting has been considered a promising approach to combat obesity and various degenerative diseases for several years. Recently, there have been increasing numbers of people who suspect that it also increases physical performance. But the facts are still thin.
British cycling was the first to experiment with the effect of ketone bodies on performance. Chris Froome won the Tour de France four times between 2013 and 2017.
A quarter of what we eat is enough for us to survive. The remaining 75 percent feed the medical and pharmaceutical industries, who make money from the abundance of the western lifestyle and the diseases that follow from it. This provocative thesis comes from the book “The Intermittent Fasting Revolution” by the American Mark P. Mattson. The neurobiologist holds a chair at Johns Hopkins University in Baltimore and is one of the world’s leading researchers on aging.
Mattson’s theory is based on the assumption that the constant excess of food has led our organism into a permanent overload. As a result, he lacks the time to regenerate. It’s like an athlete training without recovery.
This constant overfeeding became a feature of Western society. We snack around the clock, putting our pancreas under constant stress. The consequence: obesity, high blood pressure, type 2 diabetes.
The reversal of this, a temporary drastic reduction in calorie intake, puts the body in a state of autophagy, in which the organism sorts out damaged cells or, to a certain extent, recycles them. Japanese cell biologist Yoshinori Ohsumi was awarded the 2016 Nobel Prize in Physiology or Medicine for his research in this area.
If Yoshinori Ohsumi’s conclusions are correct and Mark P. Mattson’s research is correct, this would be a medical revolution and a kind of holy grail, if not for eternal youth, then at least for a long life without the various diseases of civilization that accompany the aging process. Mattson’s research indicates slower cell aging and prevention of most common cancers and degenerative brain diseases such as Alzheimer’s and Parkinson’s.
Mattson’s prescription: Shut up and take a break
Last but not least, Mattson’s recipe for targeted meal breaks would also be a remedy against the rampant obesity of society not only in the USA, but increasingly also in Europe. His formula is pretty simple: shut the door and take a break. The approach has become something of a mantra in the fight against obesity in recent years. The interval or intermittent fasting is intended to switch the body from carbohydrate to fat metabolism and thus force it into the state of so-called ketosis. In this he draws the energy from the fat reserves, but also from the muscle mass.
The common forms of intermittent fasting are 16:8 or 5:2, the calorie intake is completely or at least drastically reduced for 16 hours or two days a week. A documentary on the BBC science program “Horizon” made this type of diet an overnight hit in the British Isles in 2012. For a long time, world-renowned scientists such as the Italian gerontologist Valter Longo at the University of Southern California (UCLA) in Los Angeles or the German naturopathic professor Andreas Michalsen at the Charité in Berlin have been researching the influence of meal breaks on the human organism.
BBC Documentary: Eat, Fast, Live Longer.
According to Mark P. Mattson, the potentially performance-enhancing influence of meal breaks is interesting for the sports-loving population. In his book, Mattson cites Oxford University, which conducted five separate studies involving 39 professional cyclists in the run-up to the London 2012 Summer Olympics and concluded that the ketone bodies produced when the body uses its fat stores for energy increase the production of adenosine triphosphate in the mitochondria.
Because it is relatively complex and sometimes difficult to get into the state of ketosis, the researchers tried to artificially supply the athletes with synthetically produced ketone bodies, so-called ketone esters.
The facts about fasting are still thin
If you ask Swiss nutritionists like Paolo Colombani or Joëlle Flück, you will learn that the evidence base on the effect of a calorie-reduced diet on athletic performance is relatively thin. Paolo Colombani is the author of the bestsellers “Fette Mistakes” or “DeFlameYou!”, which deal with the silent inflammation in the body. He received his doctorate from ETH Zurich, where he researched the connections between nutrition, physical activity and health as a scientist and lecturer for almost 20 years.
Colombani says: “Intermittent fasting does not have to be a fundamental reduction in energy intake. It is often enough to shift the time window in which energy is supplied.” In sports, the aim is to optimize the efficiency of fat metabolism in order to conserve carbohydrate reserves in the muscles’ glycogen stores, which are available for rapid peak performance. He describes fasting as a kind of “yin and yang of the body”. “According to the current state of knowledge, it makes sense not to eat constantly, but to repeatedly disturb the metabolism and thus train the cells.” Colombani says that, just like in muscle training, the cells also need a stress stimulus in order to maintain or even increase their efficiency.
Fasting aims to keep the metabolism going. But you have to be careful not to get into a permanent energy deficit. The sports and nutrition scientist Joëlle Flück, who heads the Swiss Sports Nutrition Society and advises the Swiss cycling association Swiss Cycling, argues similarly.
Flück also speaks of an edge transition. “Athletes who train on a relatively large scale, as is the case in cycling or other endurance sports, must ensure that there is enough energy in the body, otherwise there can be slower regeneration or hormonal imbalances, which can lead to e.g can lead to the absence of menstruation in women.”
The so-called ketone esters, which the British researchers experimented with, are listed by the Swiss Sports Nutrition Society as C-supplements, which have little or no benefit for the athletes. Flück also refers to the lack of long-term studies. Most scientific studies in connection with intermittent fasting were carried out almost exclusively on rodents such as mice and rats because corresponding human studies are very difficult to implement due to their extremely long time horizon.
The promising perspectives of calorie reduction
However, that does not change the promising perspectives that open up a fundamentally or at least temporarily reduced calorie and nutrient intake. Flück says that carbohydrate-reduced or time-limited food intake could have great potential, especially for less active people who have lost their metabolic abilities due to the constant excess of food. The question is: what is my goal? Do I want to lose weight and revive my metabolism?
At the same time, Flück says that it is still important to ensure that you consume enough protein to prevent the loss of muscle mass. In competitive sports in particular, insufficient attention is often paid to adequate protein intake. This point generally speaks against intermittent fasting.
Paolo Colombani says it’s almost impossible to lose weight with exercise alone. The energy consumption in practically all activities is too low for this. But it is important not to simply give up exercise because it is important for health.
He sees the key to success in a combination of both: fasting and exercise. “The metabolic activation only works through physical activity.” And the less glucose is available from the muscle depots, the faster the body enters the state of ketosis, which, according to the latest research by world-renowned scientists such as Mattson or Longo, not only melts body fat, but also has a protective effect on the brain and cell aging.
Longo is now also researching at UCLA the effect of fasting not only in cancer prevention but also in treatment during chemotherapy. Because cancer cells feed primarily on sugar, initial studies indicate that fasting could not only make the therapy more efficient, but also better tolerated. This contradicts all current medical school opinions and therefore makes oncologists hesitate to make corresponding recommendations to patients. This is also because fasting people run the risk of developing a mineral deficiency. However, says Colombani, this can be prevented with targeted supplementation.
Nutrition is hardly an issue in the training of medical professionals
Colombani criticizes that the influence of nutrition in the training of prospective doctors in Switzerland is still hardly an issue and that there is hardly any research on sports nutrition that can be taken seriously. This may also be due to the complexity of the matter. Colombani says: “There are no blanket recipes that work for everyone. The functioning of the body is brutally complicated.”
A lot in Switzerland is therefore still left to the good old try-and-error principle. You try and see how your body reacts and what works for you personally. Ironically, in the energetically demanding long-distance triathlon with physical exertion of eight hours and more, more and more professional athletes like the Swiss Jan van Berkel are trying the so-called ketogenic diet, which massively restricts the intake of carbohydrates and relies on fat burning to provide energy.
Joëlle Flück suspects that such a form of nutrition can have a positive effect on metabolism and performance during ultra-endurance performance, such as at an Ironman or in a cycle race such as the Race Across America. The triathlete van Berkel also had positive experiences with it and improved his performance on the final marathon course.
However, the results of a study published by the Australian Catholic University in 2021 dampen overly high expectations. Professor Louise Burke, one of the world’s leading scientists in sports nutrition and an advisor to the Australian Olympic team since 1996, conducted a study of walkers on a low-carbohydrate, high-fat diet. The diet is said to have turned top athletes into fat-burning machines, but it hasn’t fundamentally improved their performance. Over ten kilometers, they stayed an average of six percent below their best times, which they had achieved on the usual carbohydrate-heavy diet.