Intermittent fasting
[8] Adverse effects of intermittent fasting have not been comprehensively studied, leading some academics to point out its risk as a dietary fad.
[9] The US National Institute on Aging states that there is insufficient evidence to recommend intermittent fasting, and encourages speaking to one's healthcare provider about the benefits and risks before making any significant changes to one's eating pattern.
[9][13][14] Therapeutic intermittent fasts for the treatment of obesity have been investigated since at least 1915, with a renewed interest in the medical community in the 1960s after Bloom and his colleagues published an "enthusiastic report".
[16] This enthusiasm penetrated lay magazines, which prompted researchers and clinicians to caution about the use of intermittent fasts without medical monitoring.
[5] Intermittent fasting is not recommended for pregnant or breastfeeding women, growing children and adolescents, the elderly, or individuals with or vulnerable to eating disorders.
[74] A 2019 meta-analysis found that intermittent feeding may be more beneficial for premature infants, although better designed studies are required to devise clinical practices.
[76][77] A meta-analysis found intermittent feeding had no influence on gastric residual volumes and aspiration, pneumonia, mortality nor morbidity in people with a trauma, but increased the risk of diarrhea.
[2][11][12] Religious fasting practices may only require abstinence from certain foods or last for a short period of time and cause negligible effects.
"[90] One review found similarities between Ramadan and time-restricted feeding, with the main dissimilarity being the disallowance of water drinking with Islamic fasting.
[11] Negative effects of Ramadan fasting include increased risk of hypoglycemia in diabetics, as well as inadequate levels of certain nutrients.
This type of fasting would be hazardous for pregnant women, as it is associated with risks of inducing labor and causing gestational diabetes, although it does not appear to affect the child's weight.
[88] Ramadan diurnal intermittent fasting is associated with healthier lifestyle behaviors and a reduction in smoking rate by more than 50% among university students.
[10] Given the lack of advantage and the increased incidence of diarrhea, European guidelines do not recommend intermittent feeding for people in intensive care units.
[96][97] The New Zealand's Ministry of Health considers that intermittent fasting can be advised by doctors to some people, except diabetics, stating that these "diets can be as effective as other energy-restricted diets, and some people may find them easier to stick to" but there are possible side effects during fasting days such as "hunger, low energy levels, light-headedness and poor mental functioning" and note that healthy food must be chosen on non-fasting days.
[105][106] As of 2019[update], interest in intermittent fasting led some companies to commercialize diet coaching, dietary supplements, and full meal packages.
