The warmer the water, the more oil you strip away. Most people don't soap up every inch of their body, and some places (crotch, under arms, etc) are just gener

The warmer the water, the more oil you strip away. Most people don't soap up every inch of their body, and some places (crotch, under arms, etc) are just generate more oil, and they get the soap. So with the water cooler, most of your body retains much of its oil, and our friendly bacteria can deal with excess. But if you use HOT water, you remove oil everywhere, and so the body needs to make more. Animal fat is chocked full of vitamins, and everything the body needs. 50 years ago, before canola oil was a thing (Canada made this palatable, it was only used in animal feed before), and soy oil was used, everything was made with animal fat. I remember my mom making pies with animal fat, I remember her cooking with animal fat, people ate butter, drank whole milk, this list goes on. Couple that with the fact that animals used to be more fatty. We've been breeding them for leanness, and in fact Canada used to be at the fore of this, and in the late 70s Canada had pork leaner than US beef! So in a short period, we've moved away from butter and milk fats, had our animal fat marbling in the meat reduced, and we now throw away things like bacon fat (if we even eat bacon!), instead of using that fat to cook with, or bake with. Essentially, some people eat 1/100th the animal fat their parents did. I'm not saying we should necessarily revert to 50+ years ago. However, I think we've over done it. And one thing to consider here? We're not like cars coming off an assembly line Humans have variability in diet requirements. Some need more animal fat. Some need none. Some have genetic predispositions for vitamin deficiencies, too. So if you find yourself with dry skin, more vitamin D, or more animal fat may be necessary. It's not like Bob, Dick, and Jane all need exactly 24milligrams of animal fat per day! Bob may need 10x that, Dick none, and Jane in the middle. Lastly? Vitamin D improves the ability for the skin to make oil.