Eating a 500 kcal/day vegan diet 2 days per week contributes to better health
By ANAHAD O'CONNOR MARCH 7, 2016 2:27 PM
Fasting to improve health dates back thousands of years, with Hippocrates and Plato among its earliest proponents. Dr. Mattson argues that humans are well suited for it: For much of human history, sporadic access to food was likely the norm, especially for hunter-gatherers. As a result, we’ve evolved with livers and muscles that store quickly accessible carbohydrates in the form of glycogen, and our fat tissue holds long-lasting energy reserves that can sustain the body for weeks when food is not available.
“From an evolutionary perspective, it’s pretty clear that our ancestors did not eat three meals a day plus snacks,” Dr. Mattson said.
Across the world, millions of people fast periodically for religious and spiritual reasons. But some are now looking at the practice as a source of health and longevity.
Valter Longo, the director of the Longevity Institute at the University of Southern California, initially studied fasting in mice that showed that two to five days of fasting each month reduced biomarkers for diabetes, cancer and heart disease. The research has since been expanded to people, and scientists saw a similar reduction in disease risk factors.
Dr. Longo said the health benefits of fasting might result from the fact that fasting lowers insulin and another hormone called insulinlike growth factor, or IGF-1, which is linked to cancer and diabetes. Lowering these hormones may slow cell growth and development, which in turn helps slow the aging process and reduces risk factors for disease.
“When you have low insulin and low IGF-1, the body goes into a state of maintenance, a state of standby,” Dr. Longo said. “There is not a lot of push for cells to grow, and in general the cells enter a protected mode.”
Critics say that health benefits or not, various forms of intermittent fasting are too impractical for most people.
The 5:2 diet, for example, advocates eating without restrictions for five days and then consuming just 500 calories — roughly the equivalent of a light meal — on each of the other two days of the week. Another regimen, called alternate-day fasting, involves eating no more than 500 calories every other day.
The 5:2 diet, in particular, is backed by “promising” studies that show that it lowers weight and improves blood sugar, inflammation and other aspects of metabolic health, said Joy Dubost, a registered dietitian and a spokeswoman for the Academy of Nutrition and Dietetics, the country’s largest organization of dietitians. She noted that fasting isn’t appropriate for pregnant women, people with diabetes and people on medications.
“Most people who do this understand that it’s not about binge eating,” Dr. Dubost said. “But they like that it gives them the freedom not to worry about calories, carbs and other restrictions on days when they’re not fasting.”
Krista Varady, an associate professor of nutrition at the University of Illinois at Chicago, has studied the effects of alternate-day fasting on hundreds of obese adults. In trials lasting eight to 10 weeks, she has found that people lose on average about 13 pounds and experience marked reductions in LDL cholesterol, blood pressure, triglycerides and insulin, the fat-storage hormone.
Dr. Varady found in her research that intermittent fasting was easiest when people ate a moderately high-fat diet and were allowed to consume up to 500 calories on their fasting days. In her studies, 10 percent to 20 percent of people usually find the diet too difficult and quickly stop. Those who stick with it typically adjust after a rocky first few weeks.
“We’ve run close to 700 people through various trials,” Dr. Varady said. “We thought people would overeat on their feast days to compensate. But people for some reason, regardless of their body weight, can only eat about 10 or 15 percent more than usual. They don’t really overeat, and I think that’s why this works.”
In 2011, Dr. Mattson and his colleagues reported a study of the 5:2 program that followed 107 overweight and obese women. Half of the subjects were assigned to eat no more than 500 calories each on two consecutive days each week. A control group was assigned to follow a low-calorie diet.
After six months, both groups had lost weight. But the intermittent fasting group lost slightly more — about 14 pounds on average — and had greater reductions in belly fat. They also retained more muscle and had greater improvements in blood sugar regulation.
Dr. Mattson’s interest in intermittent fasting grew out of work on animals that showed that alternate-day fasting protected mice from strokes, Alzheimer’s and Parkinson’s disease, and consistently extended their life spans by 30 percent. Dr. Mattson and his colleagues found that alternate-day fasting increased the production of proteins that protect brain cells, enhancing their ability to repair damaged DNA. Fasting, he said, acts as a mild stress that makes cells throughout the body stronger, shoring up their ability to adapt to later insults.
In this way, intermittent fasting is like exercise, which causes immediate stress and inflammation, but protects against chronic disease in the long run. Eating fruits and vegetables may have a similar effect. While very large doses of antioxidants can cause cancer in humans, moderate amounts of exposure can make cells more resilient, Dr. Mattson said.
“There is overlap between the way cells respond to exercise, to fasting, and even to exposure to some of the chemicals in fruits and vegetables,” he added.
Dr. Mattson is now starting a rigorous clinical trial of people 55 to 70 years old who are prediabetic and at high risk for developing Alzheimer’s disease. He plans to study whether intermittent fasting may slow cognitive decline.
Effects of Greek Orthodox Christian Church fasting on serum lipids and obesity.
CONCLUSIONS: Adherence to Greek Orthodox fasting periods contributes to a reduction in the blood lipid profile including a non-significant reduction in HDL cholesterol and possible impact on obesity.
Calcium, nutrient and food intake of Greek Orthodox Christian monks during a fasting and non-fasting week.
CONCLUSIONS: The periodic vegetarianism recommended by the Greek Orthodox Church contributes to the favourable profiles of several biomarkers of health among this sample of monks. The fasting rituals described are an important component of the traditional diet of Crete and should be emphasised in nutrition education programmes promoting this Mediterranean eating pattern.
Differences in nutrient intake during a Greek Orthodox Christian fasting and non-fasting week, as assessed by a food composition database and chemical analyses of 7-day weighed food samples.
Greek Orthodox fasting rituals: a hidden characteristic of the Mediterranean diet of Crete.
The longevity and excellent health status of the population of Crete has been attributed to its lifestyle and dietary habits. The impact of Greek Orthodox Christian Church fasting on these dietary habits has never been studied. One hundred and twenty Greek Orthodox Christians living in Crete participated in a 1-year prospective study. One half of the subjects, who fasted regularly (fasters), and sixty non-faster controls were followed longitudinally for the three main fasting periods over 1 year; Christmas (40 d), Lent (48 d) and the Assumption (15 d). Pre- and end-holy days measurements were performed in each fasting period including: 24 h dietary recall, blood collection and anthropometric measurements. Based on the 24 h recall, fasters as compared with controls had lower intakes of end-holy days dietary cholesterol, total fat, saturated fatty acids, trans-fatty acids and protein (P < 0.001). Fasters presented a decrease of 753 kJ (180 kcal) in end-holy days energy intake (P < 0.05) compared with an increase of 573 kJ (137 kcal) in the controls (P < 0.05). Fasters had a decrease in end-holy days Ca intake (P < 0.001) and an increase in end-holy days total dietary fibre (P < 0.001) and folate (P < 0.05), attributed to their higher consumption of fruit and vegetables in end-holy periods (P < 0.001). There were no differences for other vitamins or minerals between pre- and end-holy periods in both groups except for vitamin B2. The Orthodox Christian dietary regulations are an important component of the Mediterranean diet of Crete characterised by low levels of dietary saturated fatty acids, high levels of fibre and folate, and a high consumption of fruit, vegetables and legumes.
This is particularly important, because experts say that in our country where 22.5% of the population is obese, "fasting, which is a key element of the Greek Mediterranean diet, can give a solution to the problem of obesity in the most healthy way."
Vlachos explained the proper role for fasting, or abstaining from food. "We have to eat, but a person should not be controlled by the passion to eat," he said. "We don't fast because we hate food, nor do we simply fast for health reasons. We fast in order to heal the passion of gluttony ... to apply some self-control, self-discipline. To the degree that this healing takes place, to the same degree also a person comes to know God," he said.