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Intermittent Fasting: Common Sense or Too Good to Be True?

Happy National Obesity Care Week! Did you know that only 1-2% of individuals with the condition of overweight/obesity receives medical care for this condition? Did you know that health care and pharmaceuticals for the condition is excluded from many health plans, has to be "opted into", and coverage only “kicks in” after a person develops a health condition associated with the condition? Did you know overweight/obesity is the leading cause of preventable death in the United States now? Did you know that obesity rates have risen and it is estimated that by 2030, 50% of the population in America will have obesity? The Obesity Action Coalition is one group active in addressing conditions like weight stigma, bias, discrimination, and access to equitable care. It is a cause about which I am passionate! It affects many people in many ways, and it is immensely treatable!


One question that naturally follows the alarming statistics noted above is, why has the condition of overweight/obesity become so prevalent, and why has it been so resistant to public health and other measures? Healthy People 2020 was a group of measures put forth by large institutions in 2010 to help combat obesity. Unfortunately, none of its goals were met. The prevalence of obesity has not decreased and the prevalence of super obesity has increased. Research has shown, in a nutshell, that 80% of a person’s natural weight is genetics (and epigenetics) and environment. In addition, factors like weight positive medications, orthopedic injuries, and medical conditions add to weight gain. Some people who opine that obesity is less of a disease and more of a lifestyle argue that human genetics have not changed. While this is not necessarily true, as epigenetics can change the expression of genes from one generation to another, what if we look more closely at the environmental factors? We live in a very obesogenic society, or one which promotes weight gain. One way in which that is true is the shift in the timing of caloric intake. When humans evolved, food supply was not consistent and ever present. Therefore, humans adapted to tolerate periods of intermittent fasting. In more recent history, such as when work patterns were such that people worked on farms, or in manufacturing, calorie intake was highest in the morning and during the early and mid parts of the day. The old pattern was a large breakfast, hearty lunch, and then a light supper before bed. Today, we do not work active jobs, for the most part, but in addition to that, most of the time, the timing of calorie intake is opposite: people skip breakfast or have a light breakfast, may work through lunch, then come home and consume more than half their daily calories at night at the “family dinner”. We also live in a 24 hour society, in which many people work swing shifts or graveyard shifts or just stay up really late at night. We are all aware of the fact that society currently promotes productivity over activity (sitting at your computer), and the food environment is one of ultra processed foods so that the typical American diet is 53% cabohydrate. The new research now is on the circadian effect of calorie intake. So, now only does what you eat matter, but when you eat it matters, too.


So, a dietary pattern that has received a lot of attention lately and somewhat turned into the “latest and greatest” new thing in weight loss, perhaps since “keto” is sort of old news now, is intermittent fasting (IF). What does the data show about IF and its efficacy for weight loss and health benefits? There is a lot of research on this topic. In the studies, they follow a few methods. The most common one for assessing the effect of IF on weight loss is to compare it to simple calorie restriction (CR). In calorie restriction, a person simply consumes less calories every day, such as 300 to 500 calories less per day, but all the days are the same and the timing is not specified. Most of the studies look at weight loss at 8 to 13 weeks. In a nutshell, the research shows that IF does not provide weight loss that is superior to calorie restriction, but may be better tolerated by some and may have additional cardiometabolic benefits compared to calorie restriction such as improved insulin sensitivity, for the same amount of weight loss. However, the drop out rate was still greater than 20%. The studies show that the optimal feeding period is 8 am to 2 pm. Note that this is the opposite pattern than most people follow from my anecdotal observations, in which they elect an early phase intermittent fast of skipping breakfast, which I fear, is simply rationalizing the circadian rhythm / nutrient intake discordance that theoretically contributed to the increased prevalence of obesity in the first pl