Do cold showers really make your skin tighter?
Cold showers do not make your skin tighter; frequent showering can actually damage the skin barrier and cause dry skin, regardless of the water temperature.
Cold showers do not make your skin tighter. The two available studies say something quite different: frequent showering can actually damage the fatty layer and moisturising substances in the outermost layer of the skin. That is more likely to lead to dry, flaky skin than to a firmer or tighter appearance.
Cold weather is also cited in the same research as a factor contributing to dry skin. The combination of cold air and regular showering can deplete the skin barrier further. No direct mechanism by which cold showers would tighten the skin is described anywhere in the available studies.
The only source in this review that mentions 'skin becoming tighter' concerns a serious disease in which the body produces excessive connective tissue. That is an entirely different situation and in no way comparable to what people mean when they say that a cold shower tightens the skin.
In short: the idea that cold showers structurally tighten your skin is not supported by this research. If you want to protect your skin, it is wiser not to shower too frequently or for too long, regardless of the water temperature.
Two observational sources on dry skin as a result of showering and cold weather; one case report on skin tightening as a disease manifestation. No RCTs, no mechanistic skin research specifically into cold showers.
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.
Does drinking lots of water really help against dry skin and wrinkles?
Drinking extra water probably helps a little with dry skin, especially if you were chronically under-hydrated, but its effect on wrinkles has not yet been proven. Make sure you drink enough, but do not expect a dramatic result for your skin.
Does coffee dry out your skin?
Drinking coffee does not demonstrably dry out the skin; the research points rather in the opposite direction. If you experience dry skin, the cause is likely to be found elsewhere.
Does sleep deprivation age your skin faster?
Sleep deprivation demonstrably worsens your hydration, elasticity, and wrinkles, after as little as one poor night. Aim for consistently adequate sleep, and combine it with sun protection for the best result.
What actually works against skin aging?
Using sunscreen daily is the best-supported way to slow skin ageing, supplemented by not smoking, moderate alcohol consumption and sufficient sleep. Cosmetic options such as thread lifts and honey in creams have a weaker or not yet sufficiently proven basis and call for a critical weighing of the risks.
Does your skin get thicker or thinner as you age?
Your skin thins at two levels with age: that is well established. Retinoid creams have the most support if you want to slow that process; discuss stronger variants (such as tretinoin) with your doctor or dermatologist.