Does intermittent fasting lower your cholesterol?
Intermittent fasting probably lowers total cholesterol and LDL modestly, but its effect on 'good' HDL cholesterol is unclear and long-term data are limited. It is a worthwhile strategy as a complement to, not a replacement for, proven treatments.
Intermittent fasting lowers total cholesterol by an average of roughly 6 to 7 mg/dl and LDL cholesterol (the 'bad' cholesterol) by 5 to 6 mg/dl compared with people who do not fast. That is a modest but statistically reliable effect, demonstrated in several large pooled analyses.
Triglycerides, another type of blood fat, also fall, but timing matters: short-term fasting of 12 weeks or less can actually cause a temporary rise in triglycerides. With longer fasting periods that reverses into a reduction of 6 to 13 mg/dl.
On HDL cholesterol, the so-called 'good' cholesterol, intermittent fasting has little clear effect. In most short-term studies HDL barely changes. Only in fasting programmes lasting six months or longer did researchers observe a small increase, but even those results are too inconsistent to carry much weight.
For people with metabolic syndrome or a fatty liver the outcomes are mixed. Some studies found improvements in the cholesterol profile, others did not. The study groups are small and the follow-up periods are short, so how safe and effective intermittent fasting is for these groups over the longer term remains unclear.
One major caveat applies to everything: the studies vary enormously in approach. Time-restricted eating, alternate-day fasting, the 5:2 diet and Ramadan fasting have all been grouped under 'intermittent fasting', yet they are barely comparable. As long as that variation remains so large, the conclusions must be considered preliminary.
This answer is based on several large pooled analyses covering dozens of human studies. The direction of the effect on total cholesterol and LDL is reasonably consistent, but the variation between individual studies is high, which limits certainty. For HDL and for specific patient groups such as people with metabolic syndrome, the evidence is thin and the results are contradictory. All researchers emphasise that the fasting programmes differ too greatly from one another for definitive conclusions, and that longer studies are lacking.
Can intermittent fasting cause constipation?
Intermittent fasting can temporarily cause constipation, but in people who already suffer from constipation as a bowel syndrome, the same dietary pattern appears to help instead. It depends on your personal situation.
What are the benefits of combining sauna with an ice bath?
The combination of sauna and ice bath demonstrably lowers cortisol and promotes blood flow after exercise, but whether it delivers more than the individual methods has not yet been established. Feel free to use it as a recovery ritual, but do not expect proven benefits beyond those of sauna or ice bath separately.
Does fasting or intermittent fasting help prevent cancer?
There is no evidence that fasting prevents cancer in humans; the animal results are promising but contradictory. If you want to address excess weight as a way of reducing risk, intermittent fasting can be a tool for that, but do not expect a direct cancer-preventive effect.
Is intermittent fasting worth it?
Intermittent fasting helps with weight loss and improves blood glucose and insulin, but over the longer term it does no better than simply eating less. If the fasting structure helps you stick to it, it is worth it; do not expect additional health benefits that come for free.