If doing the same thing over and over and expecting different results is a fruitless endeavor, what does this say about intermittent fasting research? About a year ago I wrote about some of the less than sparkly research on this perennially trendy method of dieting. The more than 300 intermittent fasting studies from 2022 offer more of the same.
A few studies, including one I’ll discuss shortly, did Look promising, but they had concerning flaws. I also came across some intermittent fasting studies from the 1960s and 1970s that confirmed that there really is nothing new under the sun when it comes to dieting — and if any of these diets worked, they wouldn’t work. intermittently fall out of favor. I will give credit to these early studies for the truthful audacity of some of their language. A 1970 study even used the term “intermittent famine.” Indeed.
But back to the present. Overall, this latest round of research continues to find that intermittent fasting is no better than good old-fashioned calorie restriction for weight loss and improving health markers such as blood sugar and cholesterol levels. Considering that calorie restriction hasn’t been shown to be good for those things either — except maybe in the short term — that’s not a good recommendation for intermittent fasting.
A study, published last spring in the New England Journal of Medicine, compared time-restricted feeding — restricting eating to an 8-hour window each day — with daily calorie restriction and found no difference. Because participants were followed for only 12 months, we don’t know if the observed benefits persisted over that period.
These meager results reflect two major studies in recent years, both published in JAMA Internal Medicine. The first trial took 100 participants for a year and found no differences in weight or health outcomes between fasting on another day – eating 25% of the calorie requirement one day and 125% the next – and restricting calories to 75% of the calorie requirement each day. day. The second study of a similar size found that time-restricted feeding was also no better than eating throughout the day.
Now I want to highlight one of the flawed studies from 2022. When the results of this small randomized clinical trial from China, which concluded that intermittent fasting could reverse type 2 diabetes, was published in December, it got a lot of good press from writers who I suspect didn’t read the entire study. (It’s behind a paywall.) I’ve read the entire study, and Houston, we’re in some trouble. First, there are the ethical issues: The researchers enrolled participants and completed most of the study before registering it with the clinical trials registry. That’s a big no-no, which is why the study should never have been published. It also appears that the researchers may have only enrolled people they were sure would be successful. This means that the results cannot reasonably be applied to real, everyday people. Of the 36 participants randomly assigned to the fasting protocol, less than half achieved “remission,” and those were likely people who had had diabetes for a long time.
What worries me about the attention paid to this research is that there is more than one type of diabetes and many people are converting to intermittent fasting. A 2020 article published in the Journal of the Endocrine Society recounted the case of a 58-year-old woman with stable type 1 diabetes — an autoimmune disease in which the body stops making insulin altogether — who began a ketogenic intermittent fasting diet based on advice from a friend. She ended up in the emergency room with diabetic ketoacidosis. That’s when the body doesn’t have enough insulin to allow blood sugar into the cells for energy, so it breaks down fat for fuel, resulting in a dangerous buildup of ketones in the blood. She was lucky enough to get emergency care quickly as she could have died.
Another thing that worries me about the continued popularity of intermittent fasting is what it could mean for older adults. I recently had two family members in their 70’s who started fasting every morning because their doctor recommended it for weight loss. There are so many problems with that, I hardly know where to start.
First, once you hit your thirties, your body’s default setting is to break down muscle rather than repair it. To maintain muscle and possibly build new muscle, be mindful of it by exercising and eating enough protein. Not only does research show that more protein is needed to kick-start muscle building as we age, but the timing of that protein is important.
Eat three meals a day with enough protein — about 25 to 30 grams or 3.5 to 4 ounces — at each, and you give your body three chances to build new muscle cells. If you skip a meal, or if you eat a meal with little protein, you miss one of those opportunities. It doesn’t matter if you eat a lot of protein with another meal — say, an 8-ounce steak or a huge chicken breast. Your body can only break down about 4 ounces of that meal’s steak or chicken breast into the amino acids that are the building blocks of new muscle cells. The rest is simply converted into usable energy or stored as fat. So it’s not about getting enough protein in a 24-hour period, it’s about distributing that protein throughout your day.
The bottom line is that the increasing amount of human research does not show that intermittent fasting is better than calorie restriction for weight loss, and there is no good evidence that either method leads to long-term weight loss. Any form of calorie restriction weight loss involves muscle loss (yes, even if you also exercise), but intermittent fasting also reduces the likelihood of eating a protein-rich, muscle-supporting meal. Maintaining muscle is important for healthy aging, and not just because muscle loss increases the risk of falls, which can lead to fractures. Just some food for thought.