Low-Carb Diets: Hidden Dangers?

Steve felt a searing pain in his back that felt like someone had stabbed him with a knife and twisted it to increase the pain. Sweat poured from his forehead and he began to hyperventilate. He laid down on his back, put his knees up and tried to breathe slowly, but that only made things worse. A crescendo of spasm progressed up his side like a tidal wave before it plunged into his lower abdomen and groin. He was in excruciating pain and nothing he did made things better.
Steve’s wife rushed him to the hospital where he underwent an exhaustive series of tests to determine the cause of his agony. The diagnosis— a large kidney stone was lodged in his ureter, the long narrow tube that carries urine from the kidney to the bladder. The cause— the Atkins diet. The diet is rich in animal proteins and calcium oxalate, both of which increase the risk of kidney stones. The high-protein, low-carbohydrate diet has led to a sharp rise in the condition, particularly in young women.

Steve followed the famous low-carbohydrate diet faithfully for more than a year, but he paid a big price. The doctor put him under and inserted a stent— a metal tube that looks like it’s made from chicken wire— into his urinary tract and then bombarded his pelvis with sound waves. Unfortunately, the treatment didn’t work right away, leaving Steve in constant, unbearable pain. The stone finally broke up after two months of treatment and the agony finally ended.
The problem with most weight loss diets is that few people stay on them long enough to provide a clear picture of their effectiveness or safety. Most people give up after a few weeks and never experience the negative effects of a diet. Steve Blechman— the co-publisher and Editor-in-Chief of FitnessRx and the person described in the anecdote— is an exception.

Steve didn’t need to lose weight; he followed the Atkins diet for one year as an experiment. He is 51 years old and four percent body fat (most men his age are 25-35 percent fat), lean and muscular, and a fitness fanatic— not the typical candidate for the Atkins diet. He is a driven person with incredible self-discipline and is thoroughly trained in nutrition, biochemistry and exercise physiology. His knowledge and experience gives us a unique perspective on what can happen to someone who actually follows the diet faithfully.

More than 20 million Americans follow the Atkins weight loss plan. Famous people such as former Vice President Al Gore, actresses Renée Zellweger and Catherine Zeta-Jones, and the singers known as the Spice Girls have embraced the diet. Dr Atkins’ New Diet Revolution has sold more than 15 million copies. It has had such an impact that the diet has almost made carbohydrate a dirty word. Research studies indicate that low-carbohydrate diets are very effective for rapid weight loss, but we know little about their long-term safety or effectiveness.

Low-Carb Diet Basics

Diets, such as the Atkins, South Beach and Protein Power diets, are low in carbohydrates and high in proteins and fats. Compared to traditional weight loss diets, the Atkins-type diets contain about the same fat intake, but contain much less carbohydrate and more protein. Animal fats and proteins from meat and dairy products make up as much as 90 percent of the calories of these diets.

The body prefers to use carbohydrates as fuel and save fats for emergencies. Millions of years of development encouraged our genes to maintain and preserve fat stores. The body makes it easy to store fat, but makes it very difficult to lose it. For centuries, this served us well because people on the edge of starvation could survive for days on their own fat stores if they couldn’t find any food.

Our genes controlling metabolism and fat storage are identical to those of our ancestors thousands of years ago. Only, ancient humans didn’t have ready access to processed foods loaded with saturated fats and simple sugars, junk foods and the availability of fast food restaurants. Their diets were high in protein, monounsaturated fats and complex carbohydrates.
The problem with simple sugars is that they stimulate insulin. The pancreas secretes this hormone in response to high blood sugar levels. Insulin is essential for transporting sugar into the cells, but it also promotes fat storage. Insulin stimulates fat storage in fat cells by turning off an important chemical called hormone sensitive lipase that breaks down fat so the body can’t use it as a fuel. It also promotes a chemical called acetyl CoA carboxylase that stimulates fat storage. An important goal of low-carb diets is to keep insulin release to a minimum. This allows your body to use more fat for energy and helps you lose weight.

Two studies published in the New England Journal of Medicine in 2003 and a new study published in May, 2004, in the Annals of Internal Medicine showed that the Atkins diet helped people lose more weight than people following a low-calorie mixed diet or a high-carbohydrate diet. Surprisingly, the Atkins diet reduced markers of heart disease, such as blood triglycerides and insulin resistance. Critics of the diet say weight loss caused the decrease in triglycerides rather than the composition of the diet. The researchers counter by saying that weight loss is the purpose of the diets, so it is a positive finding that low-carbohydrate diets improve markers of heart disease.

People lose weight on low-carb diets mainly because they take in fewer calories than they use through metabolism and physical activity. Also, they lose more water while on the diet because they deplete carbohydrate stores from muscle tissue and the liver. The body stores carbohydrates as glycogen (blood sugars linked together). Each gram of glycogen is bound to three grams of water. Low carbohydrate intake depletes the glycogen stores, which causes considerable water loss.
Low-carb diets are high in protein, which help suppress appetite. Proteins are made from amino acids, which can be converted to sugar in the liver. Proteins act like blood sugar timed release capsules to maintain energy levels and prevent hunger. The body produces chemicals called ketones that suppress appetite (and give you bad breath). Also, high protein intake stimulates thermogenesis in which the body loses energy (calories) as heat rather than storing it as fat. So, Atkins-type diets may work better than normal weight loss plans because ketones and sustained blood sugar levels suppress appetite and the high protein intake boosts metabolism and helps people burn more calories.

The Downside of Low-Carb Diets

Low-carbohydrate diets are good for losing weight, but we don’t know the long-term effects on health and longevity. Low-carb diets help people lose weight quickly, but do they form the basis of a lifelong nutritional program? About 50 percent of subjects in Atkins studies drop out because it’s too difficult to stay on the diet. More than 3,500 studies involving more than 15,000 scientists reported a link between eating large amounts of meats, poultry, eggs and dairy products and heart disease, cancer, kidney failure, constipation, gallstones, diverticulosis (intestinal irritation) and hemorrhoids. In a recent study from Duke University comparing people on low- and high-carbohydrate diets, the Atkins subjects suffered a higher incidence of constipation (68% vs. 35%), headache (60% vs. 40%), bad breath (38% vs. 8%), muscle cramps (35% vs. 7%), diarrhea (23% vs. 7%), general weakness (25% vs. 8%) and skin rash (13% vs. 0%).
Constipation: Nearly 70 percent of subjects suffer from constipation due to low intake of fiber found in fruits, vegetables and whole grains. Taking a fiber supplement, such as Metamucil (sugar free), three times a day helps.
Heart disease: More women die from heart disease than any other health problem. High-protein/low-carbohydrate diets promote the intake of unhealthy amounts of cholesterol, trans fats, saturated fats and protein that increase the risk of heart disease.

Dr. Richard Fleming, a nuclear cardiologist and founder of the Fleming Heart and Health Institute in Omaha, Nebraska, does not agree that carbohydrates make people fatter than other foods. He maintains that obesity is caused by over-consumption of calories and it doesn’t matter whether those calories are carbohydrates, fats, or proteins.
His research shows that the high fat content of the Atkins diet promotes heart disease by raising blood fats and triggering inflammation in the inner lining of the arteries. Blood flow to the heart decreased by an average of 40 percent after one year on the Atkins diet and there were increases in inflammatory markers in the blood, called C-reactive protein, that’s predictive of heart attacks.
Many heart disease researchers think inflammation of the walls of the arteries supplying the heart is the leading cause of coronary artery disease and heart attacks. A low-saturated fat diet given to the control group improved blood flow to the heart by more than 40 percent. Dr. Fleming concluded that high-protein/low-carbohydrate diets are too dangerous even for a short time.

Research from the Philadelphia Veterans Affairs Hospital (2003), led by Dr. Frederick Samaha, helped promote the Atkins diet craze in America. A one-year follow-up of the original Atkins subjects showed that their weight loss was the same as those on a mixed diet, but heart disease risk factors remained lower. This is the first study showing that staying on the diet for more than a year had positive health effects, but that the difference in weight loss was temporary. The most recent Atkins study from Duke University gave subjects extensive food supplements that may have prevented side effects.

Exercise: The real reason most women diet is to improve appearance. They mistakenly equate weight loss with looking good. Unfortunately, you lose nearly as much muscle tissue as fat when you lose weight through diet without exercise.
Vigorous exercise is difficult on a low-carb diet because carbohydrates are the main fuel during exercise above 65 percent of maximum effort. Exercise increases muscle mass, a tissue that burns many calories and makes it easier to maintain lost weight. Also, increased muscle mass gives you a sexy, active, healthy-looking body. Steve Blechman noticed a dramatic and abrupt increase in energy level during exercise when he increased the carbohydrate content of his diet.
People wanting to lose weight should look at the habits of people who successfully lost weight and kept it off. The National Weight Control Registry (NWCR) established by scientists from the University of Colorado Health Sciences Center in Denver includes more than 2,900 people who lost an average of 66 pounds and maintained the required minimum weight loss of 30 pounds for an average of five years. The profiles of these people were remarkably similar— they exercised for 60-90 minutes per day and cut down on calories and fat intake. Nearly 80 percent ate breakfast every day. Less than one percent of these “successful losers” followed low-carbohydrate Atkins-type diets.

Nutrients: Limiting complex carbohydrates, particularly fruits and vegetables, may have long-term health consequences because of deficiencies in vitamins E, A, thiamin, B6, folate, calcium, zinc, magnesium, potassium and fiber. In a study of nearly 60,000 people, Harvard scientists found that women who ate diets high in fruits, vegetables, whole grain breads, cereals, fish and low-fat dairy products lived longer than those who ate few of these foods. The study showed that eating a variety of healthy foods was more important than avoiding unhealthy foods. Nutrients in fruits, vegetables and whole grains fight free radicals that help trigger heart disease, cancer, diabetes and aging. Free radicals are like biological rust that breaks down cell membranes and attacks vital genes in the cells.

Bone loss: Osteoporosis (decreased bone density) is a serious health issue for women that can lead to debilitating or deadly fractures later in life. Inadequate calcium intake, lack of exercise and irregular reproductive hormones can contribute to bone loss and can weaken bones— even in young women. Low-carbohydrate diets decrease bone density in many women. Calcium losses in women on the first phase of low-carbohydrate diets (severe carbohydrate restriction) are 65 percent above normal. During the maintenance phase of the diet, which allows more carbohydrates in the diet, calcium losses averaged 55 percent above normal. Following a diet that accelerates calcium loss increases the risk of bone fractures.

Kidneys: Low-carb/high-protein diets speed the loss of kidney function in people with early problems, but not in people with normal kidneys. Unfortunately, 20 million Americans have reduced kidney function but don’t know it because there are usually no symptoms. So, people on high-protein diets may be unknowingly damaging their kidneys. Women with high blood pressure or diabetes and older adults are more likely to have impaired kidney function and should not follow the Atkins diet.

Low-carb diets promote kidney stones: The diet disturbs acid-base balance, which promotes kidney stones, particularly among young women. Diets high in animal proteins and calcium oxalate double the threat of developing kidney stones. Also, diets low in fruits and vegetables deprive the body of nutrients that counteract the negative effects of the diet. The incidence of kidney stones among women has increased along with the popularity of low- carb diets. Also, sexual activity increases the risk of urinary tract infections. Sexually active young women also get more kidney stones because of antibiotics used to treat urinary tract infections. Antibiotics deplete the body of organisms that normally protect against developing kidney stones.

Steve Blechman’s Low-Carb Diet Experience

Steve Blechman’s experimental experience with the diet is interesting and instructive. He followed the traditional Atkins plan for three weeks. He ate mainly meats, eggs and cheese. In that short time, his cholesterol increased from a healthy 160 milligrams per deciliter to a borderline high level of 210.
He modified the diet for the remainder of the one-year experiment. He restricted carbohydrates to less than 50 grams per day, but ate foods containing only healthy fats, such as fish, nuts, olive oil and green, leafy vegetables. He followed a low-carbohydrate version of the Mediterranean diet. He ate no animal fats and restricted saturated fat intake to a minimum. His cholesterol returned to 160, but he still developed kidney stones after being on the diet for 12 months. His capacity for aerobic exercise increased almost immediately when he returned to a moderate carbohydrate (zone 40/30/30) diet containing healthy complex carbohydrates. He feels strongly that high-protein/low-carbohydrate diets work, but you have to take precautions to avoid the unhealthy side effects.

Making Low-Carb Diets Healthier

People like low-carbohydrate diets because they help them lose weight quickly with little or no exercise. The diets are effective— at least in the short run. If you want to lose weight quickly with a low-carb/high-protein diet, follow the principles suggested by Steve Blechman to reduce the risk of kidney stones and other health problems associated with the diet.

  • Drink plenty of water. The National Academy of Sciences recommends letting thirst be your guide to satisfying water requirements. Most women on the diet should drink 2.7 liters of water a day (a liter is roughly one quart).
  • Eat healthy fats. Avoid animal products (meat, cheese, and whole eggs) and eat fish containing omega-3 fatty acids that may reduce the risk of coronary artery disease. Use oils containing healthy fat, such as olive and canola oils. Nuts, beans and avocados contain healthy fats that taste good, are low in carbohydrates, but don’t contribute to heart disease.
  • Eat moderate amounts of carbs. A moderate to low-carb diet consisting of 40 percent carbs, 30 percent fat and 30 percent protein will help you lose weight, but will be less likely to have the side effects of the Atkins diet. Low-carb/high-protein diets increase the acid load on the kidney (from sulfur amino acids and keto-acids) and increase the risk of kidney stones.
  • Eat more alkaline phytonutrient rich vegetables and fruits (green, leafy vegetables and almost all fruits) to avoid kidney stones.
  • Take potassium, calcium citrate and magnesium supplements to prevent kidney stones.
  • Take calcium with meals to bind oxalates from vegetables such as spinach. Drink high-calcium mineral water, such as Pellegrino water, with meals.
  • Emphasize good, healthy carbs, such as whole grains and beans that bind and speed the excretion of oxalates.
  • Exercise every day and train with weights at least two days per week. This will improve your metabolism and help you fight fat.

The main thing is to keep at it: exercise regularly, eat healthy foods, avoid saturated fats and simple sugars and minimize stress. Don’t be too hard on yourself if you deviate from the program every once in a while. Begin anew tomorrow and try to live a healthy lifestyle one day at a time.

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