A Review of the Different Types of Popular Diets

At times it can be confusing to pick a diet. There are many different diets being marketed at any given time. How is a person to know how they differ and which one is right for them? Categorizing the diets into groups that share basic characteristics is a good way to start understanding popular diets.

Low carbohydrate diets

Low carbohydrate diets are among the most popular diets around. Despite this popularity, most people don’t really understand how the diet works. Here’s the low-down on low-carb diets.

A carbohydrate is a sugar is a carbohydrate

Before getting too far into low carbohydrate diets, it is important to understand that, to the body, there is little difference between different carbohydrate foods. Bread or candy, it makes no difference. The only difference with reference to its carbohydrate content is the amount of time it takes to digest. Those that take a long time to digest are referred to as complex carbohydrate because they are long chains of sugar. Simple carbohydrates take no time at all to digest and are called simple because they are very short chains of sugar. Before any carbohydrate gets into the body, it is broken down into short chains. So to the body, carbohydrate and “sugar” are identical. It is only the tongue that can distinguish between the too.

A tale of two fuels

The body relies on 2 things for fuel, sugar (remember this is just another name for carbohydrate) and fat. There is a priority as to which fuel the body will burn first when both are available. Carbohydrate will generally be burned before fat. So when you eat a meal containing both sugar and fat the body will burn the sugar and store the fat. The fat will stay where it is stored until sugar is no longer available. Unfortunately, when sugar is no longer available, the brain triggers hunger so that you will eat more sugar, leaving the fat right where it is. “A moment on the lips, forever on the hips” as they say.

Most of the sugar you eat in your diet is reserved for the brain and nervous system. Some have interpreted this as meaning that carbohydrate is the body’s “preferred” fuel. If this were so, wouldn’t the body store carbohydrate instead of fat? Rather than carbohydrate being the “preferred” fuel, carbohydrate is the body’s most “convenient” fuel under normal circumstances. This is why getting the body to use stored body fat instead of carbohydrate can be difficult.

Because the body will burn carbohydrate before it will burn fat, if you continually supply carbohydrate, the body will never dip into stored fat. There would be no reason to. The idea behind a low carb diet is to continue to feed the body essential protein, but eliminate, or greatly reduce the amount of carbohydrate, so that the body must use stored body fat for fuel. The liver then makes the necessary sugar for the brain, while the muscles switch to using fat.

Nay Sayers have a point…sort of.

Mobilizing stored fat when sugar intake is low is a natural function of the body. Even when sugar made in the liver runs low (such as during exercise), the brain can switch over to burning “ketones”. Ketones are made from fat, of which there is an abundant supply already in the body. This is why low carb diets are often referred to as “ketogenic diets”.

Opponents of low carb diets voice concern over the body’s production of ketones. They feel this will cause a condition caused by poorly managed type-I diabetes called keto-acidosis. In the diabetic patient, insulin cannot be produced; this causes ketone production to rise far above normal, and can lower the pH of the blood. This has not been shown to happen in people without type-I diabetes. Without the ability to produce insulin, ketone levels can rise far above what naturally occurs when normal people consume less carbohydrate.

In a nutshell

Here are a few summary points to take home:

  • The body burns either sugar (A.K.A. carbohydrate) or fat for fuel.
  • If sugar is available the body won’t burn fat. It is better to burn the sugar when available because it can’t be stored.
  • You must limit the availability of sugar to get the body to dip into stored fat for fuel.

A low carb diet may not be for everybody, especially those who don’t like meat. But if you have tried other diets and are looking for a new diet to try, the low carb approach just might be the ticket.

40/30/30 and Zone diets

The term “zone” refers to optimizing the body’s metabolism through a diet containing a certain ratio of protein, carbohydrates (carbs) and fat. To Barry Sears, who coined the term “zone” with respect to diet, this zone can be achieved through a special diet which controls the body’s production of a hormone called insulin.

Much ado about Insulin

Insulin is a very important hormone. It is what allows our cells to take up carbohydrates that we eat. Without insulin we develop diabetes. Diabetes is the condition when there is no insulin (type I) or when the tissues become insensitive to it (type II). As a result blood sugar rises and begins to cause secondary problems, which can be fatal over time.

Insulin is also able to affect the levels of other important chemicals in the body called eicosanoids. Eicosanoids are involved in everything from blood pressure to inflammation. There are few if any tissue in the body that are not responsive to eicosanoids.

Some eicosonoids are bad (increase pain, inflammation, raise blood pressure) and some are good (don’t increase pain, don’t promote inflammation, lower blood pressure). Aspirin for example and other non-steroidal anti-inflammatory drugs work by blocking the production of eicosonoids (NSAIDs) and thereby can reduce pain and inflammation.

Insulin promotes the production of bad eicosanoids. According to Barry Sears, you can lower the production of bad eicosonoids and increase the production of good eicosanoids by following a 40/30/30 eating plan. This means 40% calories from carbohydrate, 30% calories from protein, and 30% calories from fat.

As with the very low-carb diets, lowering insulin also greatly facilitates fat loss. Because carbohydrate intake is relatively low, and always eaten with protein and fat, blood sugar levels do not rise quickly. When blood sugar levels do not rise quickly, insulin stays fairly low and steady. This can increase the ability of a meal to provide a sustained sense of energy and curb hunger. The lower insulin also decreases the tendency of energy to be taken up by fat cells.

Fat ain’t all bad

Finally, the zone diet places great emphasis on eating “good fats”. Just as some amino acids from protein are essential to life, so are some fats. Fats are important for cell structure, hormone production as well as for energy storage. Certain essential fats called “omega-3” fatty acids have many healthful properties. Diets high in omega-3s have been shown to reduce the risk of cardiovascular disease, diabetes, high blood pressure, and stroke. That’s one fancy fat!

In summary, a diet containing 40% carbs, 30% protein, and 30% fat may have health benefits beyond simple weight reduction, especially if essential fats are included. Plus, with a diet relatively generous in both carbs and fat, fixing appropriate meals is a snap!

Low fat diets

There is probably no diet more common than a “low fat” diet. As dieters embraced it, an entirely new faction of the food industry was invented and has thus far thrived. All our favorite processed foods were soon further processed into “reduced fat” or “fat free” versions. So why all the fuss about fat? It can’t be all that bad…can it?
The cheering section

The pressure to reduce fat intake came from two camps, first the dieticians focused on fat because it is the most calorie dense foodstuff. Second came the heart doctors who realized that certain kinds of fat in the diet were highly associated with the risk of developing cardiovascular disease. The two groups together present a very influential argument for Americans to reduce the fat in their diets.

The logic of Low-Fat eating

When trying to lose weight, you must burn more energy than you eat. Burning more energy is easy, just get up and get going. Eating less energy is the hard part. The easiest way to eat less energy is to focus on reducing the foods that have the most energy in them, namely fatty foods.

Fat has 9 calories per gram. Protein and carbohydrate have only 4 calories per gram. Fat is also devoid of fiber making it even easier to eat a lot of it. On the positive side, because fat is so calorie dense (meaning you can fit a lot of fat into a small package) you can cut out a lot of fat without cutting out a lot of food.

Don’t throw out the baby with the bath water

Not all fats are created equally. I think you will be happy to learn that fats have gotten a bad reputation because of the consequences of eating to many “saturated” fats. Not all fats are saturated and not all fats pose the health problems that saturated fats do.

Fats serve a broader purpose than simply providing texture, taste and calories to your diet. Just as some amino acids are essential to life, so are some fats. Fats are important for cell structure, hormone production as well as for energy storage. There are many problems experienced during states of malnutrition due to the lack of essential fats.

The association between saturated fat intake and cardiovascular disease is well known. Much of this association centers on cholesterol. Saturated fat raises blood cholesterol and LDL levels more than any other element in the diet. Studies have shown that increased saturated fat intake increases LDL (bad cholesterol) and lowers HDL (good cholesterol). (1) Cholesterol and fat, circulating in the blood, build up on the walls of the arteries. The buildup narrows the arteries and can slow or block the flow of blood. When the level of cholesterol in the blood is high, there is a greater chance that it will be deposited onto the artery walls. Over time this can lead to a narrowing of the arteries and an increased risk of heart attack.

A good high-carb/low-fat diet is one with a wide variety of fresh fruits, vegetables, whole grains, and low fat meats such as chicken, fish and lean cuts of beef. Stick to it and you will not only see the pounds come off but you will also decrease your risk of heart disease.

In Summary

You can fit virtually any diet into these three categories. You might find some variation as companies try to make their diet “appear” to be completely new, but in general they will still fit into the above categories.

I hope you noticed that I didn’t place any one diet above another. The reason I did this is because each type of diet, when combined with weights, cardio and adhered to consistently, will yield lead to significant weight loss. So the diet you chose really just depends on your preferences.

References:

1: Loktionov A, Scollen S, McKeown N, Bingham SA. Gene-nutrient interactions: dietary behavior associated with high coronary heart disease risk particularly affects serum LDL cholesterol in apolipoprotein E epsilon4-carrying free-living individuals. Br J Nutr. 2000 Dec;84(6):885-890.

Originally published: ThinkMuscle.com, January 2002

IFBB pro bodybuilder Sergei Shelestov

Photo credit: Muscletime

About Bryan Haycock

Bryan Haycock+ is an exercise physiologist and NPC judge. Bryan has been bodybuilding for over 20 years and holds certifications with the NSCA, ACE, and is a member of the American College of Sports Medicine. Bryan is currently the Editor in Chief of ThinkMuscle.com and is the founder and CEO of LifeStyleMgmt.com. Bryan is a highly sought after authority on the physiology of muscle growth and fat loss. Bryan also specializes in the management of type-II diabetes through diet and exercise.