Does a fasting-mimicking diet work better than simply eating less?
A fasting-mimicking diet has promising effects on several health markers, but whether it works better than simply eating less has not yet been demonstrated. If you want to try it, be aware that independent long-term data are still lacking and that the costs of commercial packages are a real consideration.
Three cycles of a fasting-mimicking diet (five days per month) improved several health markers simultaneously in a study of 100 predominantly healthy individuals: body weight, abdominal fat, blood pressure, fasting glucose, LDL cholesterol and inflammatory markers. The effects were greatest in people who already had elevated risk values. Another study with 102 participants who were overweight or obese showed that after six monthly cycles the proportion of people with a reduced sense of smell fell from 38% to 6%, and cardiometabolic values also improved. No serious side effects were reported.
A secondary analysis of one of these randomised studies found that three FMD cycles were associated with a median reduction of 2.5 years in biological age, measured via blood markers. There was also less insulin resistance and less liver fat, independent of weight loss. Note: the principal investigator on several FMD studies has a financial interest in the company that sells the FMD product (L-Nutra). That makes independent replication especially important before drawing strong conclusions.
The direct comparison with simply eating less is the weak point in the evidence. No study exists that pits the FMD head-to-head against ordinary calorie reduction over a longer period. Review articles conclude that both approaches can produce weight loss, but that chronic calorie reduction is difficult to sustain in practice because of psychological and social barriers. Whether the FMD performs better in the long term has not yet been demonstrated.
For people who want to lose weight or reduce cardiometabolic risks, the FMD therefore offers preliminary indications of benefit, but a straightforward continuous diet with fewer calories has at least as much supporting evidence for weight loss. The FMD is appealing for people who cannot sustain daily dietary restriction, but the higher costs (commercial package) and the absence of long-term comparative data are real drawbacks.
The evidence rests on three randomised studies totalling a few hundred participants, and several review articles. The FMD studies are too small for firm conclusions, and several were conducted or co-funded by researchers with a financial interest in the FMD product. A direct comparison between the FMD and ordinary calorie reduction in a well-designed study is entirely absent.
Which form of intermittent fasting works best?
Alternate-day fasting has the strongest short-term evidence for weight loss, but the advantage over simply eating less is small and disappears after six months. Which approach suits you best depends on what you can sustain the longest.
Does the fasting-mimicking diet, such as Prolon, actually work?
The fasting-mimicking diet improves measurable risk factors such as blood sugar, blood lipids and abdominal fat across multiple human studies. Some studies were funded by the manufacturer of ProLon, so independent confirmation carries more weight than those results alone.
Does eating less help you live longer?
In laboratory animals the effect on lifespan is well established, but in healthy humans direct evidence is lacking. A moderate and sustainable eating pattern is wiser than extreme restriction; discuss major changes to your diet with a dietitian or doctor.
Does the 16:8 schedule work better than other forms of intermittent fasting?
16:8 works better than shorter fasting windows in the short term, but over the long term it is not demonstrably better than simply eating fewer calories. Choose the approach you can sustain best.
Does fasting or eating less help your memory and concentration?
Eating less or intermittent fasting probably shows a small positive effect on memory and concentration. The evidence is there, and the effect is clearest in people who already have mild memory problems.
Does fasting or calorie restriction make the skin look younger?
Fasting and calorie restriction appear to protect the skin in animal research, but direct evidence in humans that your skin will look younger as a result is still entirely lacking. It is too early to act on this practically, although nicotinamide (vitamin B3) as a supplement has already been studied in humans for skin cancer prevention.