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Wednesday, January 26, 2011

Fatty Liver Disease: Another Reason to Avoid Obesity

An article in the January 2011 issue of the Harvard Health Letter reveals that the epidemic of obesity has increased the occurrence of fatty liver disease. Previously, most cases of fatty liver disease were related to excess alcohol consumption, but now, many cases are related to excess body fat, which can lead to Type II diabetes. Fatty liver disease affects 70-90% of those who are obese and/or have diabetes.

Abdominal obesity can lead to metabolic syndrome (elevated blood pressure and levels of triglycerides and blood sugar, and low HDL (good cholesterol). Overfilled fat cells become resistant to insulin (which lowers blood sugar by storing it in the cells) resulting in excess fatty acids in the blood. Fat then accumulates in liver cells, which can lead to inflammation and liver tissue damage.  This can in turn bring about liver fibrosis (buildup of fibrous tissue) or cirrhosis (buildup of scar tissue). Cirrhosis increases the risk of liver cancer.

Fatty liver disease increases the risk of heart attack and stroke because a fatty liver produces inflammatory factors that can promote the deposition of plaque in the arteries, leading to arterial narrowing.

The only effective treatment for fatty liver disease is to lose weight.

Bottom Line
If you want to avoid or reverse fatty liver disease, avoid gaining unnecessary body fat or lose existing excess body fat through a program of good nutrition and exercise. Both caloric restriction and exercise are essential parts of any weight-loss program.

Wednesday, January 19, 2011

As We Age, Cholesterol Level Loses Its Value as a Risk Factor

Because both a high total cholesterol level and a high LDL-cholesterol level are risk factors for heart disease, statin drugs, which lower both levels, are widely prescribed. In the U.S., more prescriptions are written for Lipitor, the most popular statin, than for any other drug. Estimates for the number of people who take statins range between 11 million and 30 million. But should so many people be taking statins? A recent analysis, in which scientists reviewed 14 studies that included data from over 34,000 patients, showed little evidence that statins prevent heart trouble in patients with no history of cardiovascular disease. And because there is some evidence linking low cholesterol levels with increased risk of death from other causes, the study authors feel that doctors should be more cautious about prescribing statins.

An important factor to consider when deciding whether or not to prescribe statins is the patient’s age. A study by Kronmal et al., entitled, “Total Serum Cholesterol levels and mortality risk as a function of age” in the Archives of Internal Medicine (vol. 153, pp. 1065-1073, 1993) examined how age affected the ability of cholesterol level to predict the risk of dying, and it showed that the predictive value declined with age.
The most important consideration when judging mortality risk is the overall likelihood of dying from any cause. In that regard, at age 40, those people with higher total serum cholesterol levels had a significantly higher all-cause mortality risk. However, the relationship declined with age, and by age 60, the relationship between total cholesterol level and all-cause mortality had vanished. By age 80, the relationship actually reversed, so that those with higher cholesterol levels were at significantly lower risk of dying.

Looking specifically at the risk of death from coronary heart disease, the death risk at ages 40, 50, and 60 years was greater for those with higher cholesterol levels, although the effect got smaller with age. By age 70, the relationship was still positive but weak, but by age 80 the relationship reversed, and those with higher cholesterol levels actually had less chance of dying.

Looking at death due to causes other than heart disease, (e.g. cancer), from age 50 on, there was a lower risk of dying as cholesterol levels rose. This apparent protective effect of cholesterol against non-heart-disease death increased with age. Seventy-three percent of 80 year-old men with cholesterol levels above 240 survived for 5 years, while only 49% of those with levels below 240 did. The effect was in the same direction but weaker for women, with a 74% and 70% 5-year survival rates for women with cholesterol levels respectively above and below 240 mg/dl. In regard to cancer alone, higher cholesterol level was associated with lower death risk.

Bottom Line
The current practice of the medical establishment of prescribing statins to anyone with a total cholesterol level above 200 appears to be unjustified. For patients with elevated cholesterol levels and a history of heart disease, statins provide a proven reduction in risk. However, for patients with mildly elevated levels and no history or heart disease, the evidence in favor of prescribing statins is weak or nonexistent. And for men above age 70, even those with cholesterol levels above 240, statins could very well increase the risk of death.

Friday, January 14, 2011

New Insights into Obesity

The December 2010 issue of the Nutrition Action Health Letter, published by the Center for Science in the Public Interest, featured an interview with Eric Ravussin, head of the Nutrition Obesity Research Center of the highly regarded Pennington Biomedical Research Center in Baton Rouge, LA. The discussion centered on new clues as to why we gain weight, and revealed the following:
  • Leptin, a hormone discovered in 1994, is produced by fat cells and  tells the brain when the cells are full.
  • When people diet and lose weight, leptin levels drop sharply, causing food cravings and weight regain.
  • Loss of 10-20% of body weight slows the metabolism and rate of caloric burn.
  • Injecting leptin can bring the metabolism back up.
  • However, most overweight people are resistant to leptin, just as Type II diabetics are resistant to insulin.
  • Using drugs to shut down hunger mechanisms doesn’t work well because the human body has developed several redundant systems to stimulate eating as protection against starvation.
  • People have natural ranges of body fat depending on their genes that control energy intake and expenditure.
  • Nutrition in the womb and infancy can affect propensity for overweight and obesity by switching different genes on and off.
  • Brown adipose tissue, which burns calories to produce body heat, previously thought to exist only in infants, was recently discovered in adults.
  • By maintaining homes at a steady comfortable temperature throughout the year, we don’t burn calories via brown fat to keep warm in winter, and we miss the appetite-suppressing effect of heat in the summer.
  • A common cold virus (adenovirus-36) makes experimental animals gain a lot of weight. Antibodies to this virus, an indication of exposure, are much more common in obese than in normal-weight people.
  • Gut bacteria can be a factor. Transplanting feces from a fat animal to a lean one results in weight gain for the latter, while transplanting from the lean to the fat animal makes the fatter one leaner. Similar transplants in humans have reduced insulin-resistance of people with metabolic syndrome, a set of symptoms indicative of heart-disease risk characterized by excess fat around the waist, low HDL, and elevated blood pressure, blood triglycerides, and fasting blood glucose.
Ravussin feels that we should tax soft drinks and other unhealthy foods while subsidizing healthy foods, create areas where kids can safely play, and make physical education mandatory so that everyone, not only the athletically-gifted, engages in physical activity,

Tuesday, January 4, 2011

Does Heavily Advertised Exercise Equipment Really Provide Advantages?

Advertisements on TV and elsewhere make it appear that, if you buy the latest innovative exercise device you will make faster and greater gains than you could using more conventional exercise equipment. Unfortunately, such claims, however seductive, do not usually stand up to scrutiny. The following articles in the December 2010 issue (vol. 24, no. 12) of the Journal of Strength and Conditioning Research highlight instances in which such equipment fails to provide any training advantage over standard exercises.

An article by Youdas et al. (pp. 3552-3562) compared the electrical activity of 4 chest, arm, and shoulder muscles of 20 subjects doing pushups using the Perfect-Pushup device and the same subjects doing standard pushups. The Perfect-Pushup device allows free horizontal rotation of the hands during the pushup movement while, during the standard pushup, the hands maintain their position throughout the movement. Pushups both with and without the device were done 3 different ways - using wide, shoulder-width, and narrow hand placements. While the results showed some small advantages of either the Perfect-Pushup or standard pushup as to the intensity of involvement of specific muscles when using particular hand positions, neither the Perfect-Pushup nor standard pushup showed any overall superiority to the other form of exercise. Hand position had a much more striking effect on muscle involvement, indicating that pushups should be done at various hand placements in order to stimulate a wide range of chest, shoulder, and arm musculature.

Another article by Youdas et al. (pp. 3404-3414) compared exercise using the Perfect-Pullup device to standard pull-ups (overhand grip) and chin-ups (underhand grip) using an overhead straight bar. The Perfect-Pullup device allows free horizontal rotation of the hands during the pull-up movement while, during the standard pull-up and chin-up, the hands maintain their position throughout the movement. Muscle electrical activity sensors were used to monitor the effort of 7 different muscle groups for 21 men and 4 women during the exercises. The results showed that, while there were some significant differences in muscle activation between the chin-up and pull-up, there were no significant differences between the Perfect-Pullup device and either the chin-up or pull-up. The authors concluded that the Perfect-Pullup device did not provide any advantage over standard pull-ups or chin-ups.

An article by Willardson et al. (pp. 3415-3421) compared the electrical activity of 3 abdominal muscles and 1 set of back muscles during 3 traditional trunk exercises and abdominal exercise using a device called the Ab Circle. Results showed no statistically significant differences in muscle activity between the Ab Circle and standard exercises. Yet the mean activity of the rectus abdominis muscles (6-pack) and lower abdominal stabilizer muscles was highest during the standard crunch, and the erector spinae (low back) muscles and external obliques (lateral waist) were most active during the side bridge. Thus the Ab Circle provided no advantage over standard calisthenic exercises for working the abdominal and low back musculature.

An article by Schoffstall, Titcomb, and Kilbourne (pp. 3422-3426) compared the electrical activity of 5 muscles involved in abdominal and hip flexion (upper rectus abdominis, lower rectus abdominis, internal obliques, external obliques, and rectus femoris) during the following isometric exercises:
- Crunch
- Supine V-up (while facing upward, back and legs rise off the ground to make a V-shape)
- Prone V-up (while facing down, butt rises up while hands and feet approach each other, making inverted V-shape) done as follows:
  • Feet on ground (no equipment)
  • Feet on FB large exercise ball
  • Feet on Power Slide
  • Feet supported by TRX suspension straps
  • Feet on Power Wheel
The results showed that:
  • All exercises stimulated the external obliques, upper rectus abdominis, and lower rectus abdominis similarly
  • The supine V-up without equipment showed greater internal oblique activity than the V-up done on the slide board.
  • The rectus femoris was less active during the crunch than during any of the other exercises. This is not surprising since the knees are specifically bent during a crunch to take the hip-flexors out of play and focus only on the abdominal muscles.
  • Overall, the prone and supine V-up exercises done without equipment provided as much training stimulus to the muscles tested as did the prone V-up using any of the commercial equipment.
Bottom Line
These studies indicate that much of the exercise equipment heavily marketed to the public provides no advantage in training stimulus over standard exercises. The only advantage of such equipment is that it provides variety, which may be important to maintain the motivation to exercise. Some exercise enthusiasts, even when informed that such equipment usually provides no shortcuts to the results they desire, may still wish to purchase them in order to keep their workout fresh, and that is fine. However, for those who would rather use their money for different purposes, there are other ways to add variety to a workout. Using standard gym equipment, a wide variety of exercises can be performed, especially using free-weight barbells and dumbbells and an overhead bar for hanging exercises.