Have you ever seen a fat cheetah?

To be fast you have to be thin. Cheetahs, the fastest animals on earth, can reach speeds of 70 MPH, but only because they are so skinny. The same principle applies to humans. It is easy to see that the athletes who win the races are very thin.

In general, given muscle power and leg speed, the lighter the load, the faster the speed. Athletes with a higher percentage of body fat will run slower than they could if they were leaner. But how does one become slimmer?

There are many different opinions on this topic, some not helpful, some even dangerous. The following review of some dietary data and new research reveals sensible and safe ways for an athlete to get leaner and stronger.

First, some basic food facts:

There are three basic food groups:

1) Proteins build muscles, organs, bones, enzymes, immune cells, and many hormones.

2) Carbohydrates are fuel for immediate use.

3) Fats provide insulation, buffering and storage for calories and help build cell membranes and some hormones.

All foods can be turned into fat if you eat too much of them. The excess of carbohydrates, proteins and fats will make you fat. A little known fact is that most of the protein we eat is converted to carbohydrates and used for fuel or stored as fat. For example, 83% of the whey and soy proteins consumed are not used to build body protein, but rather as carbohydrates.

This is why:

The protein in food is made up of amino acids strung together like beads on a chain. When a dietary protein source is digested, amino acids are released and absorbed in the small intestine. Some of these amino acids can be used as building blocks that recombine to build the proteins needed by the body. Only amino acids that are available in the correct proportions can be used to build body proteins.

How much of the protein that is digested and absorbed is used to build body proteins?

That depends on the source of the protein. Most people think that if they eat 30 grams of protein, their body will use all of those 30 grams to make new protein or to replace protein that is naturally lost each day. This is not really what happens.

Each protein source is made up of different amounts of individual amino acids. Each protein source has a different percentage of its amino acids that can be used to build body protein.

A chicken breast (raw, boneless, and skinless) is about 23 percent protein. Therefore, 3 oz (85 g) of chicken breast would contain about 19.5 grams of protein. (In a healthy person, about 2-8% of protein is indigestible, leaving at least 18 grams of digestible protein.) What’s important to know is that of these 18 grams, only about 30% (about 5 grams) is actually “used” by our bodies to make or synthesize new proteins. The rest (about 13 grams) breaks down and becomes a source of calories.

If you look at whey protein, only 16% of the amino acids are used to build protein in the body. Therefore, 84% of the amino acids are not used to make protein and only become a source of extra calories!

It is also important to understand that if amino acids from a protein source or amino acid formula are not used, in addition to releasing calories, harmful nitrogenous waste is released that must be eliminated by the body. (Excess nitrogen waste can stress the liver and kidneys, especially as we age.)

Although all food groups (fats, proteins, and carbohydrates) can be used as an energy source, only protein can provide the essential amino acids needed to build body protein. (Carbohydrates are the body’s preferred source of energy.)

So how do you get a slim body?

First. Use carbohydrates with caution. Except during intense training, avoid products that contain high-fructose corn syrup. Instead of consuming sports bars and drinks with high-fructose corn syrup, eat natural, unprocessed foods, including starchy fruits and vegetables.

Second. Avoid all refined grains (white flour, white rice, and most baked goods). They are poor sources of food for everyone.

Third. Avoid most processed foods and “fast” foods. Read food labels. If additives, preservatives, dyes, chemicals, flavors, seasonings, etc. are listed, ignore them.

Four. Avoid all foods with trans fats, fried foods, and margarine.

In general, eat mostly healthy, natural, unprocessed foods: fruits, vegetables, fish, nuts, unprocessed meats, beans, and eggs. Eat like our caveman ancestors. (Eliminate sugar and processed foods.)