When we refer to nutrition, we are referring to the nourishment of the body. There are several basic ways that we nourish our bodies ...
(The links in the following list list will take you to pages that address the subjects thoroughly. If you read down the page, each of the following nutrition items are explained more briefly.)
All this nutrition must be provided by the food you eat and the drinks you drink.
Calories have a bad rap because if you get too many of them, you get fat. On the other hand, calories are nothing but a measure of the amount of fuel you're giving your body to run itself. If you don't get enough calories, three things happen, in the following order:
You don't want that to happen. You don't want to take in too much fuel, but it's even worse not to get enough!
Calories can be nutritious!
All carbohydrates are converted to a specific type of sugar, glucose, and burned for energy, or, if they are not needed, they can be converted to fat and stored.
You have probably heard that complex carbohydrates are good for you, and that simple carbohydrates, like sugar, are bad for you.
As a scientific statement, this is preposterous; however, there is a practical sense in which we North Americans and Europeans, who are almost 100% so wealthy that we are never hungry, need to avoid simple sugars.
If you eat glucose, your body doesn't have to process it. It can go straight into the bloodstream and be burned. Since you only need a small amount of sugar—I've heard a teaspoon—in your bloodstream at one time, your body has to dump insulin into your blood to process the excess sugar.
That insulin dump is not natural; before processed foods, there was no way to dump sugar into your body like that. Insulin reactions lead to what I like to call a sugar crash. The excess insulin burns up too much sugar, leaving you with low blood sugar and no energy. Insulin reactions also lead to all sorts of health problems, the primary one being diabetes.
I try to pass on good, mainstream advice, not assertions made with no scientific evidence. The statements I just made about insulin violate this. There is no conclusive evidence that too much sugar and insulin reactions cause diabetes. Diabetes is only certainly associated with being overweight.
However, while there is no conclusive links between too much sugar and health problems, the general links are so obvious that everyone, even the strictest scientist, knows that it's a good idea to avoid the unnatural process of dumping sugar quickly into your bloodstream.
Therefore, I felt free to be loose and tell you what insulin dumps might cause.
Maybe you can relate overloading your bloodstream to sugar with flooding your car with gasoline. A little gas going into the engine is absolutely essential to making your car run. Give it too much at once, and it will choke itself to a stop.
Complex carbs are better. They have to be broken down into glucose. That takes time, and so the sugar enters your bloodstream more slowly.
Contrary to popular belief, white sugar is not the type of sugar your bloodstream burns. It is sucrose, and it, too, has to be digested and made into glucose. Your body can turn potatoes into glucose faster than it can turn sucrose into glucose.
Potatoes, however, are usually eaten with butter. The fat in butter slows down your digestion. Protein will, too, but not as much.
And, yes, that works for a Snickers® bar, too. There's enough fat in the peanuts and whatever else they put in the candy bar to stop the sugar rush. Snickers bars are cheaper than power bars in most cases, and they're every bit as good—or as bad—for you. (If you've just run two miles, a Snickers bar is actually good for you, just not as good as, say, ham and cheese on whole wheat crackers.)
"They" say that we are primarily made of water, perhaps 75% of our body mass. What is not water, however, is almost all protein.
Thus, if we were going to be comprehensive about protein, we would have to write not a page, but a complete web site.
What you need to know for nutrition purposes is this:
Finally, there are LOTS of opinions about the amount of protein you need and whether too much is bad for you. The only thing I've heard that sounds conclusive and is from reliable sources is that excess protein can leach calcium, which would make weak bones a danger.
It's hard to believe large amounts of protein is a problem because low-carb diets like the Atkins diet result in large quantities of protein and studies have shown that those on the Atkins diet are remarkably healthy in most ways after a year. The problem with low-carb diets is that people just don't stick to them longer than a year. Personally, I don't think low-carb diets are normal for humans, so our body rebels against them when we're offered carbs.
Fat has a bad rap, but it is a crucial part of your nutrition! Unless you have too much of it, it is only good. Have you ever heard of essential fatty acids?
They're called that because they're, well ... essential!
Adults need about 30% of their calories to be fat calories! Thus, while a low-fat diet may help people lose weight in the short term, it is harmful in the long term.
Low-fat diets are especially harmful to children. Small children need up to 50% of their calories to come from fat!
There are various types of fat. Only saturated fats—which you get from meat and other animal products, like milk and eggs—and hydrofats—created by man through by hydrogenating vegetable oils—are bad for you. Monounsaturated fats, such as olive oil and canola oil, are downright good for you!
Vitamins are substances your body needs to carry on its various chemical processes, but that it cannot produce itself. You have to get vitamins and minerals from food (or, in modern times, pills).
The one exception is Vitamin D, which your body creates using ultraviolet rays from sunshine.
Your body actually uses ultraviolet rays from sunshine to make Vitamin D. Sunshine also affects processes, such as melatonin production which affects your sleep patterns. There are likely others still unknown to modern medicine. Thus, while too much sunshine can cause skin cancer, too little can cause Vitamin D deficiency and is known to cause depression as well.
Vitamins can be either fat-soluble or water-soluble. That is one more problem that persons with too little body fat can run into, which is an inability to store vitamins!
I heard a quote once from a nutritionist who said, "Inside every young man with washboard abs is an aboriginal person that wishes he were a little fatter." (Well, something like that, anyway.)
Since we're about 60% water, obviously we need it, and it must be included as part of or nutrition.
You get water both by drinking and from the food you eat. For humans, however, the majority comes by drinking.
The rule generally given is "8x8." That refers to drinking eight 8-oz. cups of water each day.
The rule is dumb. Here's why:
If you drink too little water, you will get thirsty. If you still don't drink water, you will get tired or sick. If you drink too much water, you could die.
Runner's World reported once that there are deaths at marathons every year from hyponatremia. Hyponatremia is low sodium. Sodium, and other electrolytes, allow the fluids in your body to conduct electricity better. Without enough, systems in your body go haywire, and you can die.
Athletes who work hard in the heat, such as marathoners, are constantly warned to drink lots of water, but this can be highly dangerous. Dehydration will make you sick and hurt performance. Over-hydrating without replenishing electrolytes, especially sodium (from salt), can and does kill. (See this Mayo Clinic article and this one from sportsmedicine.about.com.)
If you are going to work or exercise in the sun, drink a sports drink, not water.
Of course, this is unlikely to be dangerous if you're simply working in the yard one day, both because it's not as strenuous as a marathon and because yard work is still done more by men. Men are larger and so it takes a larger amount of water to dilute their fluids.
Marathoners and other extreme endurance sports athletes, who are prone to being smaller anyway, need to take this warning very seriously.
Here's the nutrition rules for drinking water that aren't fairy tales:
One more fairy tale: Caffeinated drinks do not dehydrate you, especially if you're an athlete. Yes, they make you urinate more. So does water. Says who? How about the Mayo Clinic? ABC News' Dr. Marie Savard agrees.