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Study under review: Effect of alternate-day fasting on obesity and cardiometabolic risk: A systematic review and meta-analysis
Intermittent fasting (IF) is a popular strategy for weight loss. The term encompasses different specific diets characterized by periods of eating interspersed with longer periods of fasting, which are mapped out in Figure 1. A less common diet in humans, but one used for longer durations in animal models, is alternate-day fasting (ADF). As its name implies, ADF consists of fasting for one day and eating the next day. This can either mean fasting for 24 hours and eating for 24 hours, or most commonly, fasting for 36 hours and eating for 12 hours. One modification, used clinically to increase adherence, involves eating a small amount of calories on the fasting day (about 25% of standard, also called modified ADF). Although there is a lot of experimental support for the usefulness and efficacy of ADF in animal models, its effects in humans are still controversial.
There have been several meta-analyses comparing intermittent energy restriction (IER) interventions, which include IF and ADF, to continuous energy restriction (CER) for weight loss and cardiometabolic risk markers. Several have been covered in Study Deep Dives. However, these papers tend to lump together all types of IER, complicating interpretation of the results, and include different types of studies. To find a more specific answer to the question “Does ADF work for humans?”, the authors of this meta-analysis compared the effects of ADF against CER or control on weight-related parameters and cardiometabolic risk markers.
A popular means of weight loss is to incorporate regular periods of fasting. Alternate day fasting (ADF), in which food is ingested every other day, has been used in research and in some human trials. However, ADF has not been meta-analyzed separately from other types of IER, and randomized controlled studies specifically on ADF have not been meta-analyzed.
Other Articles in Issue #74 (December 2020)
Deep Dive: Comparing different protein sources' impact on bone turnover
Eating more plants can be healthy but may negatively impact bone health due to lower protein, calcium, and vitamin D intake. This trial examined how the same amount of protein from animal or plant sources affected bone turnover.
Deep Dive: Does low protein intake slow down chronic kidney disease progression?
Very low protein diets seem to slow progression but don't affect mortality, raising the question of whether there's a risk-benefit tradeoff. Higher quality, larger trials could shed more light on this issue.
Mini: Dietary approaches and supplements to combat chronic pain
What nutritional interventions impact different chronic pain conditions? This NERD Mini summarizes the evidence from a systematic review released earlier this year.
Interview: Jeff Rothschild, RD, CSSD, PhD(c)
What should we eat before exercise? To find out, we picked the lead author's brain of a recent review that answers that exact question!
Deep Dive: Will nitrates improve your training performance? It depends!
Nitrates provide a small but significant performance boost, but dose, timing, and your baseline aerobic fitness matters.
Deep Dive: Determining the per-kilogram effects of weight loss on lipid levels
How much do blood lipids change for each kilogram of weight lost? This study aimed to answer this question, while also exploring whether the method of weight loss (through lifestyle, drugs, or bariatric surgery) matters much.
Deep Dive: The best non-drug ways to lower blood pressure
Drugs are usually an effective way to lower blood pressure, but non-drug interventions can help a lot, too! This network meta-analysis looked at which non-drug methods are the best for lowering blood pressure.