ORIM Weekly W33 2022

EDITORIAL

Intermittent fasting continues to generate both excitement and confusion. This week, we present the current state of evidence, clarifying which fasting protocols are supported by rigorous science and which populations should approach with caution.

16:8 Time-Restricted Eating: The Evidence

A 2021 meta-analysis in the Annual Review of Nutrition pooling 27 clinical trials found that 16:8 time-restricted eating (TRE) produced modest weight loss (1.5-3% body weight) comparable to continuous caloric restriction, with additional benefits for insulin sensitivity and blood pressure. Importantly, benefits were greatest when the eating window aligned with the biological morning-afternoon, suggesting circadian alignment matters more than the fasting duration itself.

Fasting and Autophagy: Human Evidence

While animal studies demonstrate robust autophagy activation during fasting, human data is more limited. A 2021 study in Autophagy journal using autophagy biomarkers (LC3-II, p62) showed that 36-hour fasting significantly increased autophagic flux in human peripheral blood mononuclear cells. Shorter 16-hour fasts produced measurable but smaller increases, suggesting a dose-response relationship between fasting duration and cellular cleanup activation.

Who Should NOT Fast

A critical 2021 review in Obesity identified populations for whom intermittent fasting may be harmful: pregnant or breastfeeding women, individuals with a history of eating disorders, type 1 diabetics on insulin, adolescents still growing, and those on medications requiring food intake. The review emphasized that the stress hormonal response to fasting (cortisol, adrenaline) can exacerbate anxiety disorders and disrupt menstrual cycles.

Apple Cider Vinegar (Acetobacter-Fermented)

Apple cider vinegar (ACV) with 'the mother' contains acetic acid bacteria and enzymes formed during fermentation. Clinical evidence shows that 1-2 tablespoons of ACV before meals reduces postprandial glucose spikes by 20-30% by slowing gastric emptying. Some practitioners recommend ACV during fasting windows, though it technically breaks a strict fast. Its impact on AMPK activation may partially mimic fasting benefits.

Dilute 1-2 tablespoons in a large glass of water and drink through a straw before meals. Never consume undiluted ACV, which can erode tooth enamel and irritate the esophageal lining.

THIS WEEK IN BRIEF

► FASTING: Largest-ever human intermittent fasting trial (10,000 participants) launches at the University of Illinois, comparing 16:8, 5:2, and alternate-day protocols over 12 months.

► TECH: Continuous glucose monitor company Levels raises $38 million to bring metabolic health tracking to consumers, enabling real-time visualization of fasting effects on blood sugar.

► CAUTION: British Dietetic Association warns against promoting fasting to adolescents on social media, citing emerging evidence of disordered eating patterns triggered by restrictive protocols.

ORIM Tip: If you practice time-restricted eating, never skip your eating window's first meal protein. Breaking a fast with pure carbohydrates creates an exaggerated insulin spike. Always include 20-30g protein in your first meal to stabilize blood sugar and prevent muscle loss.