What They Haven’t Told You About Intermittent Fasting
The first time I heard that term, it was about a decade ago around the time I was starting college. My cousin showed me this ripped YouTuber talking about Intermittent Fasting and how he “cracked the code.” Throughout my teen years, I was obsessed with getting a six-pack and was willing to try anything. It was not long that I would be doing it and I was fairly successful with it. I did not stick to it for long although it would play a recurring role over the years for fat loss.
Is Intermittent Fasting Effective For Fat Loss?
A better way to frame it: If you ate the same amount of calories over a 24hr period, would Intermittent Fasting produce more fat loss?
A meta-analysis looked at 27 studies into short-term and long-term Intermittent Fasting protocols. They compared them to regular energy restricted diets.
At the same time calories, they looked at weight loss, cardiometabolic markers, and appetite. The results: No difference.
To sum it up: If you were in a deficit at 2,000 calories per day, it would make no difference whether you ate those calories throughout the day or in an 8hr window. The benefits are from solely the calorie restriction.
While it can make for a good tool to help create that calorie deficit, its only attributed to having a shorter eating window. To sum it up, if the individual is not in a calorie deficit, intermittent fasting makes no difference.
Longevity?
Intermittent Fasting has been cited for increasing longevity despite there being no evidence of it outside of the calorie restriction it imposes.
There has been more evidence to support normal calorie restriction improving longevity than there is for fasting. Even then, there have been misinterpretations with the calorie restriction data being tested in primates. They found that these primates saw their longevity improved by with a 30% calorie restriction.
The primates are not in a calorie restriction their entire lives as they would die from starvation. In most animal studies, calorie restriction is simply observing what animals consume normally and then restricting them by a defined % from that. Its noted that animals tend to overeat when provided free access to food.
While the animals lose a modest amount of weight, it plateaus quickly. The researchers are merely preventing them from overeating. These animals maintain a healthy weight and have better longevity than those that overeat.
The data provided above is in line with the data seen for obesity and mortality. In human studies, obesity represents about a 20% increase risk for mortality for each 5 increments in Body Mass Index (BMI) above a healthy BMI of around 22–24. A BMI of 29 would be approximated at a 20% risk. Improving longevity means having a healthy normal weight and preventing excess body fat accumulation.
Autophagy?
Advocates of Intermittent Fasting have made the argument that Fasting increases Autophagy. Autophagy is one of the pathways of cellular and protein breakdowns using the lysosomal pathway to remodel and break down old proteins into keeping cells healthy. Fasting may increase it but for how long is undetermined whereas calorie restriction has found to do the same. There has been evidence that calorie restriction by 20–30% has had powerful effects on autophagy which can go on for years. Exercise has been found to increase autophagy even if its a little bit. As Intermittent Fasting deals with a shorter eating window, autophagy can be downregulated along with the protein degratory pathway when consuming a larger food quantity.
A research paper published in the Journal of the Academy of Nutrition and Dietetics found that meal skipping and shorter meal intervals are associated with an increased risk of all-cause and cardiovascular disease mortality among US adults. 24,011 adults age 40 or older participated in the study. The objective of the study was to examine the associations of meal frequency, skipping, and intervals with the mortality.
While correlation does not equal causation, it does not help the Intermittent Fasting case. There was a 30% increase risk in all-cause mortality with the group eating 1 meal per day as opposed to the group eating 3 meals per day. When it came to the cardiovascular mortality risk, it was an 80% risk. For people who skipped breakfast, it was a 40% risk. The BMI was relatively the same across the board which helps a lot as BMI is a predictor of mortality.
Conclusion
If there is 1 thing to take from this, the fitness industry is probably no different from other industries when it comes to dogma. Oftentimes, our judgement could be clouded by superstition that may negatively influence our decision making. Intermittent Fasting is merely an example. It’s not necessarily bad, just overly hyped and I say this as someone who occasionally does it.
Study Ref [1]: Intermittent Energy
Restriction for Weight Loss: A
Systematic Review of Cardiometabolic,
Inflammatory and Appetite Outcomes
Biol Res Nurs. 2022 Jul;24(3):410–428
Study Ref[1]: Calorie Restriction-Mediated Replicative Lifespan Extension in Yeast Is Non-Cell Autonomous
Szu-Chieh Mei, Charles Brenner. 2015 Jan, 29
Study Ref[2]: BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants
Dagfinn, Aune. 2016 May, 4
Study Ref[3]: The effect of fasting or calorie restriction on autophagy induction: A review of the literature
Mohammad Bagherniya. 2018 Aug, 30
Study Ref[4]: The Effects of Calorie Restriction on Autophagy: Role on Aging Intervention
Ki Wung Chung. Hae Young Chung. 2019 Dec, 2
