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.
Combining sauna with a cold bath noticeably lowers the stress hormone cortisol. In young men, cortisol levels dropped from an average of 13.6 to 9.7 µg/ml after four alternating sauna sessions (90°C) and cold baths (10°C). Those who started with a high cortisol level saw the greatest effect. The combination had no demonstrable effect on testosterone or other sex hormones.
The combination has an acute but variable effect on the heart and blood pressure. In healthy young women, heart rate rises during each sauna round, and blood pressure peaks briefly after the first round. With repeated sessions, blood pressure subsequently falls, suggesting that the body adapts. How this plays out in older people or people with heart conditions cannot be determined from these studies.
After intensive exercise, alternating warm and cold water increases blood flow in the legs by more than 22 percent compared with passive rest. At rest, without prior exercise, the combination cancels itself out: warm water alone strongly increases blood flow, cold water alone reduces it, and together they average each other out.
Experienced winter swimmers who regularly combine the two produce more body heat in the cold than people without that habit. This suggests that the body adapts over time. However, this was found in people who had been combining the two for years, so it cannot be inferred that starting this ritual produces the same effect.
The big open question remains: does the combination deliver more than sauna or ice bath separately? A broad review study offers no definitive answer here. The opposing effects of heat and cold can reinforce each other, but can also cancel each other out. There are too few studies that directly compare the methods to give a clear answer.
This answer draws on a mix of small human studies (young men and women, winter swimmers, trained athletes) and two review studies. The findings on cortisol and blood flow were directly measured, but always in small and specific groups. One review study concludes that direct comparisons between the combination and the individual methods barely exist. The evidence is therefore too limited for firm statements about who exactly benefits, with which protocol, and compared with sauna or ice bath alone.
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.
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.