Low carb (carbohydrate), high protein diets are the latest

dieting craze. However, before you jump on the band wagon,

you may want to consider a few things:

1. Low carb (ketogenic) diets deplete the healthy glycogen

(the storage form of glucose) stores in your muscles and

liver. When you deplete glycogen stores, you also dehydrate,

often causing the scale to drop significantly in the first week

or two of the diet. This is usually interpreted as fat loss when

it's actually mostly from dehydration and muscle loss. By the

way, this is one of the reasons that low carb diets are so

popular at the moment - there is a quick initial, but deceptive

drop in scale weight.

Glycogenesis (formation of glycogen) occurs in the liver and

muscles when adequate quantities of carbohydrates are

consumed - very little of this happens on a low carb diet.

Glycogenolysis (breakdown of glycogen) occurs when

glycogen is broken down to form glucose for use as fuel.

2. Depletion of muscle glycogen causes you to fatigue easily,

and makes exercise and movement uncomfortable. Research

indicates that muscle fatigue increases in almost direct

proportion to the rate of depletion of muscle glycogen. Bottom

line is that you don't feel energetic and you exercise and move

less (often without realizing it) which is not good for caloric

expenditure and basal metabolic rate (metabolism).

3. Depletion of muscle glycogen leads to muscle atrophy (loss

of muscle). This happens because muscle glycogen (broken

down to glucose) is the fuel of choice for the muscle during

movement. There is always a fuel mix, but without muscle

glycogen, the muscle fibers that contract, even at rest to

maintain muscle tone, contract less when glycogen is not

immediately available in the muscle. Depletion of muscle

glycogen also causes you to exercise and move less than

normal which leads to muscle loss and the inability to

maintain adequate muscle tone.

Also, in the absence of adequate carbohydrate for fuel,

the body initially uses protein (muscle) and fat. the initial

phase of muscle depletion is rapid, caused by the use of

easily accessed muscle protein for direct metabolism

or for conversion to glucose (gluconeogenesis) for fuel. Eating

excess protein does not prevent this because there is a caloric

deficit.

When insulin levels are chronically too low as they may

be in very low carb diets, catabolism (breakdown) of

muscle protein increases, and protein synthesis stops.

4. Loss of muscle causes a decrease in your basal metabolic

rate (metabolism). Metabolism happens in the muscle. Less

muscle and muscle tone means a slower metabolism which

means fewer calories burned 24 hours-a-day.

5. Your muscles and skin lack tone and are saggy. Saggy

muscles don't look good, cause saggy skin, and cause you to

lose a healthy, vibrant look (even if you've also lost fat).

6. Some proponents of low carb diets recommend avoiding

carbohydrates such as bread, pasta, potatoes, carrots, etc.

because of they are high on the glycemic index - causing

a sharp rise in insulin. Certain carbohydrates have always

been, and will always be the bad guys: candy, cookies, baked

goods with added sugar, sugared drinks, processed / refined

white breads, pastas, and rice, and any foods with added sugar.

These are not good for health or weight loss.

However, carbohydrates such as fruits, vegetables, legumes,

whole grain breads and pastas, and brown rice are good for

health and weight loss. Just like with proteins and fats, these

carbohydrates should be eaten in moderation. Large volumes

of any proteins, fats or carbohydrates are not conducive to

weight loss and health.

The effect of high glycemic foods is often exaggerated. It's does

matter, but to a smaller degree than is often portrayed. Also,

the total glycemic effect of foods is influenced by the quantity

of that food that you eat at a sitting. Smaller meals have a lower

overall glycemic effect. Also, we usually eat several types of

food at the same time, thereby reducing the average glycemic

index of the meal, if higher glycemic foods are eaten.

Also, glycemic index values can be misleading because they

are based on a standard 50 grams of carbohydrate consumed.

It wouldn't take much candy bar to get that, but it would take

four cups of carrots. Do you usually eat four cups of carrots

at a meal?

Regular exercisers and active people also are less effected by

higher glycemic foods because much of the carbohydrate

comsumed is immediately used to replenish glycogen stores in

the liver and muscle.

By the way, if you're interested in lowering insulin levels,

there is a great way to do that - exercise and activity.

7. Much of the weight loss on a low carb, high protein diet,

especially in the first few weeks, is actually because of

dehydration and muscle loss.

8. The percentage of people that re-gain the weight they've

lost with most methods of weight loss is high, but it's even

higher with low carb, high protein diets. This is primarily due

to three factors:

A. You have lost muscle. With that comes a slower

metabolism which means fewer calories are burned 24

hours-a-day. A loss of muscle during the process of losing

weight is almost a guarantee for re-gaining the lost weight,

and more.

B. You re-gain the healthy fluid lost because of glycogen

depletion.

C. It's difficult to maintain that type of diet long-term.

D. You have not made a change to a long-term healthy

lifestyle.

9. Eating too much fat is just not healthy. I know you've

heard of people whose blood levels of cholesterol and

triglycerides have decreased while on a low carb, high

protein diet. This often happens with weight loss, but it

doesn't continue when you're on a diet high in fat.

There are literally reams of research over decades that clearly

indicates that an increase in consumption of animal products

and/or saturated fat leads to increased incidence of heart

disease, strokes, gall stones, kidney stones, arthritic

symptoms, certain cancers, etc. For example, in comparing

countries with varying levels of meat consumption, there

is a direct relationship between the volume of meat consumption

in a country and the incidence of digestive cancers (stomach,

intestines, rectal, etc.).

Fat is certainly necessary, and desirable in your diet, but

they should be mostly healthy fats and in moderation.

Manufactured / synthetic "low fat" foods with lots of added

sugar are not the answer. Neither are manufactured / synthetic

"low carb" foods with artificial sweeteners or added fat. By

the way, use of artificial sweeteners has never been shown

to aid in weight loss and they may pose health problems.

According to Dr. Keith-Thomas Ayoob of Albert Einstein

College of Medicine in New York, "In my experience,

unless you're willing to throw out decades of research,

you cannot ignore that diets chronically high in saturated

fats are linked to heart disease," Dr. Ayoob is also a

spokesman for the American Dietetic Association

and says that low carb, high protein diets are an attempt

at a quick fix and not a long-term lifestyle change.

10. As someone recently told me, "it must work - people

are losing weight". People that are truly losing fat on

low carb, high protein diets, are doing so because they

are eating fewer calories - that's the bottom line. There

is no magic - the same can be done on a healthy diet.

11. Low carb diets are lacking in fiber. Every plant-based

food has some fiber. All animal products have no fiber. A

lack of fiber increases your risk for cancers of the digestive

track (because transit time is lengthened) and cardiovascular

disease (because of fibers effect on fat and cholesterol). It

also puts you at a higher risk for constipation and other bowel

disorders.

12. Low carb diets lack sufficient quantities of the the many

nutrients / phytonutrients / antioxidants found in fruits,

vegetables, legumes, and whole grains, necessary for health

and aiding in prevention of cancer and heart disease. In fact,

you need these nutrients even more so when you're consuming

too much fat as is often the case on a low carb high protein diet.

13. Amercans already consume more than twice the amount

of protein needed. Add to that a high protein diet and you

have far too much protein consumption. By the way, most people

don't realize that all fruits, all vegetables, all whole grains,

and all legumes also contain protein. Animal products contain

larger quantities of protein, but that may not be a good thing.

Excess dietary protein puts you at a higher risk for many health

problems: gout (painful joints from high purine foods which are

usually high protein foods), kidney disease, kidney stones,

osteoporosis (excess dietary protein causes leeching of calcium

from the bones). By the way, countries with lower, healthier

intakes of protein also have a decreased incidence of

osteoporosis.

14. Low carb, high protein diets cause an unhealthy

physiological state called ketosis, a type of metabolic acidosis.

You may have heard the phrase, "fat burns in the flame of

carbohydrate". Excess acetyl CoA cannot enter the Krebs

Cycle (you remember the old Krebs Cycle) due to insufficient

OAA. In other words, for fat to burn efficiently and without

production of excess toxic ketones, sufficient carbohydrate

must be available. Ketosis can lead to many health problems

and can be very serious at it's extreme.

15. Bad breath. Often called "keto breath" or "acetone

breath", it's caused by production of acetones in a state of

ketosis.

So why the low carb, high protein craze? I believe there are

several reasons.

A. Weight loss (mostly muscle and muscle fluid) is often

rapid during the first few weeks. This causes people to think

they're losing fat rapidly.

B. It gives you "permission" to eat the "bad foods": bacon,

eggs, burgers, steak, cheese, etc., and lots of fat.

C. Many see it as the new "magic" they've been looking for,

although it's been around, in various forms, since the

1960's.

The good news is that there is a very healthy way to lose

weight, feel energetic, and to greatly increase your chances

of keeping it off. But that's another article.

References:

- Brooks, G, Fahey, T: Exercise Physiology - Human Bioenergetics

and its Applications. John Wiley and Sons, 1984.

- Cheatham, B, Kahn, CR: Insulin Action and Insulin Signaling

Network. Endocrine Review 16:117, 1995

- Fain, JN: Insulin Secretion and Action. Metabolism 33:672, 1984.

- Fitts, RH: Cellular Mechanisms of Muscle Fatigue. Physiological

Review 74:49, 1994

- Griffin, James, Ojeda, Sergio: Textbook of Endocrine

Physiology. Oxford University Press, 2000

- Guyton, A, Hall, J: Textbook of Medical Physiology. W.B.

Saunders Company, 2000.

- Herzog, W: Muscle Function in Movement and Sports. American

Journal of Sports Medicine 24:S14, 1996

- Hoffman, JF, Jamieson, JD: Handbook of Physiology: Cell

Physiology. Bethesda: American Physiological Society, 1997

- Kimball, SR, Vary, TC, Jefferson, LS: Regulation of Protein

Synthesis by Insulin. Annual Review Physiology 56:321, 1994.

- McArdle, William, Katch, Frank, Katch, Victor: Exercise

Physiology - Energy, Nutrition, and Human Performance.

Lea and Febiger, 1981.

- Mcdougall, MD, John: The Mcdougall Plan. New Century

Publishers, 1983.

- Simopoulos, AP, Pavlou, KN: Nutrition and Fitness. Basel:

Karger, 1997

copyright 2004 by Greg Landry, M.S.

Author and exercise physiologist, Greg Landry,

offers free weight loss and fitness success stories

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