Low Carbohydrate Diets
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Question: Another question if I may? Have you ever heard
of a dietary supplement that is called blue-green algae? If so, what
do you think of it? Thanks so much for your help. |
| Question: I've read a couple of the Q&A articles under "Ask the Dietitian" and noted your concerns on low-carbohydrate diets. You are probably familiar with the Atkins diet. My wife is currently on this diet (2 weeks now) and has lost approximately 10 pounds. I guess the idea is that the carbohydrates are kept under 20 gm/day initially, while protein & fat are essentially unlimited, no calorie count restriction. This being the case, do the concerns that accompany a low carbohydrate/low calorie diet apply also to a low carbohydrate diet with unlimited protein? You mention low carbohydrate diets of fewer than 900 calories not providing enough protein for muscles and organs and not supplying an adequate resource for glucose. What about 20 gm/day of carbohydrates and, say, 500 gm/day protein and 30 gm/day of fat, for example. Does this supply enough protein for adequate glucose production & protein reserve? I don't think all the weight my wife lost was water. She has been consuming approximately 2000 calories/day total, limiting the carbohydrates to 20 gm max. and not really watching anything else. Is she headed for trouble or is the high protein/fat intake compensating for the missing carbohydrate? If she were to transition from a carbohydrate-restricted diet to a fat-restricted diet at a later time, would this prevent regaining weight? Answer: Yes the concerns are similar when restricting carbohydrates whether or not you have unlimited protein or even fat in your diet. Your wife is in ketosis because of restricting carbohydrates. Your body can scavenge from dietary protein and fat to supply glucose. But the hoops your body has to jump through to do that requires more effort than depleting your body's stores of glycogen. Glycogen is converted to glucose rather easily. The problem is when you've depleted your stores of glycogen (stored glucose in muscle and lean tissue) your body turns to burning muscles or organs (lean muscle tissue) and dietary protein or fat to provide blood glucose to supply energy needs. When this happens, your basal metabolic rate drops because you have less lean muscle tissue burning calories and your body thinks its starving and cuts back on energy requirements. The human body's genetic material is 12 million years old and still thinks in terms of feast or famine. A 25+-year-old female needs 50 grams of protein per day. Protein is used to build and repair lean muscle tissue. This would not provide enough glucose to prevent ketosis. A diet of 500 grams of protein per day would be equal to 71.4 ounces (4.5 pounds) of meat, fish or poultry. Do you really think you wife can eat that much? (Did you mean 50 grams?) Also, since most sources of protein also have fat, I would guess that a diet that included 500 grams of protein would also inherently contain at least 214 grams of fat. (One ounce of lean meat, fish or poultry has 7 grams of protein and 3 grams of fat.) A diet high in protein usually turns off the appetite (as do the ketones being produced) and puts a strain on the kidneys. Proteins are large molecules and your blood is constantly filtered by your kidneys. Twenty grams of carbohydrate is only 80 calories. If the remaining calories are protein and fat, she could be eating 35 ounces (2.2 pounds) of lean meat. Could this be possible? I would bet that a lot of the weight your wife has lost is water because each gram of glycogen in muscles and lean tissue holds 3 grams of water. When you deplete glycogen, you lose water. Muscles and lean tissue are 70% water; fat is only 15% water. Usually these low carbohydrate diets encourage 8 glasses of water per day. This is to help flush the ketones out of the body through the kidneys and to prevent dehydration. One method of determining if you are dehydrated is to grab a pinch of skin on the back of your hand and let go. If you skin snaps back flat, you probably are not dehydrated. Also, look at the color of your urine. During the day it should be colorless and odorless unless you take Vitamin C supplements which will turn your urine yellow. Look at a ten pounds box of butter. Does you wife think she has lost that much fat in two weeks? Probably not. What is your wife going to eat when she goes off her low carbohydrate diet? When she starts to eat a low fat diet, she will experience weight gain just due to re-hydration. A weight loss program that is more like her normal eating habits with fewer calories and less fat with a regular exercise program has been shown to be the most successful to keeping weight off long term. |
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Ask the Dietitian SM Copyright © 1998 Joanne Larsen MS RD LD