A second opinion on Dr. Oz’s advice: 10 of the good doctor’s tips debunked
Not all the star physician’s tips hold up to scientific scrutiny
Physician Mehmet Oz became an international superstar through his regular appearances on Oprah Winfrey’s top-rated chat show and writing for Oprah Winfrey’s magazine, O. He now stars in a show of his own, dispensing health and weight-loss advice.
According to Oz, doctors dispense facts to their patients with the expectation that they will use that information to live a healthier life. Generally, that approach is a total failure.
“People don’t change what they do based on what they know, they change based on what they feel,” Oz, tells his audiences.
The good doctor bridges the gap by telling his mostly female fans that they are responsible for bringing the message home and that they are responsible for the health of their husbands and children.
What Oz sells is a combination of common sense — what he calls ancient wisdom — and science-based medical advice. Some of his top tips for health are built on a firm scientific foundation, while others don’t quite withstand scrutiny.
Here are the facts, based on peer-reviewed science.
1) Eat a high-fibre breakfast. Fibre slows the transit of food through the intestine and increases satiety, promoting weight loss.
The facts: The evidence that fibre promotes weight loss is weak. Companies that sell soluble fibre supplements as weight loss products have been disciplined by the U.S. Federal Trade Commission for exaggerating weight loss claims. A very high-fibre diet can decrease levels of so-called bad cholesterol, but evidence that high-fibre diets reduce the risk of heart disease is mixed and weak.
2) Never eat on an empty stomach. By the time your body has responded to the food you are shovelling in, you can eat three times what as much food as you need. Snack before dinner to reduce ghrelin levels 30 minutes before you start to eat.
The facts: The effects of the hunger-stimulating hormone ghrelin are not well understood. Ghrelin levels rise before meals and fall after eating. Obese people appear to have less ghrelin than people of normal weight, which makes its role in obesity questionable.
3) Work your muscles. Resistance training is key to maintaining muscle mass and preventing osteoporosis. Every kilo of muscle burns 50 times more calories per day than a kilo of fat.
The facts: Meta-analysis of randomized controlled trials of post-menopausal women finds that resistance training offered a modest benefit in bone density in the lumbar spine but mixed or insignificant effects at the hip and femoral neck. Training appeared to improve bone density most in women who are undergoing hormone replacement therapy.
Muscle does burn slightly more energy at rest that fat, but only about eight calories per kilo, and not 50 times more than fat. However, resistance training combined with a low-calorie diet does result in greater loss of fat and reduced loss of lean muscle.
4) Take a deep breath. To displace stale air from the lungs and deliver a dose of nitric oxide, breathe in deeply, so your belly button goes out and pull it back toward your spine when you exhale.
The facts: This falls into the category of ancient wisdom (yoga) mixed with very preliminary science. Nitric oxide plays a role in cellular metabolism and relaxes blood vessels, but whether deep breathing produces enough NO to affect processes throughout the body is not known. There is no stale air in your lungs, each breath replaces about one third of the air, maintaining a steady balance of CO2. Excessive deep-breathing can reduce CO2 levels dangerously, constrict the blood vessels and cause loss of consciousness.
5) Sleep on a schedule. Deep sleep is the most important sleep; it promotes muscle mass by generating growth hormone. Turn off the computer and the TV well before bed time, so your brain releases melatonin. Relax before bed, sleep in a cool room and wake up at the same time every day.
The facts: Chronic sleep deprivation is a relatively recent phenomenon, becoming widespread only in the past 50 years. Lack of sleep results in appetite dysregulation and is associated with obesity, diabetes, depression and fatigue. TV and computer time in the evening does reduce production of melatonin, a hormone that regulates alertness and promotes sleepiness.
6) Never have soft drinks with a meal. Fructose in soft drinks short-circuits the body’s natural leptin-based satiety signal. Not only will you consume 160 calories in your soda pop but you will eat an extra 125 calories in food at that meal.
The facts: Leptin is known to have a role in appetite suppression and obese people may be leptin-resistant. Fructose — used as a sweetening agent in soft drinks — does not stimulate insulin production as much as glucose and may interfere with the brain’s ability to signal satiety, which can lead to overeating.
7) Diet soda does not help you lose weight. If the brain expects more nutrients after tasting a sweet drink, it will insist that you provide them. Fruit juices diluted with water are a better way to reduce calories and acquire nutrients.
The facts: Diet sodas alone will not help you lose weight, but neither are they known to promote weight gain as recent headlines blared. Rats given artificially sweetened drinks will overindulge on real sweets given the chance, but a calorie-reduced diet that includes diet soft drinks can result in weight loss in humans.
8) Supplement for nutrition. Take vitamins A, B, C, D and E, as well as minerals calcium, magnesium, selenium and zinc. Take half a multi-vitamin in the morning and half in the evening, because you will pee them away.
The facts: Vitamin D has been shown to help prevent heart disease. Health Canada recently increased the daily recommended intake of vitamin D. High-dose trials of vitamin E, however, led to increased risk of death. A review of clinical trials of vitamin supplements by the American Heart Association failed to find any beneficial effect on the incidence of heart disease or the risk of death.
9) Reduce your risk of Alzheimer’s with a diet rich in Omega-3 fatty acids and turmeric.
The facts: Omega-3 fatty acids have been shown to provide a protective effect against vascular dementia and are known to have positive effects on cognition in older adults, but have so far been ineffective on people who already have Alzheimer’s disease. Turmeric has been used in India traditional medicine to treat inflammatory disease and brain injury and appears to protect rats against neuronal degeneration.
10) More women die of heart disease than breast cancer, so the benefits of alcohol outweigh the risks.
The facts: Despite an extensive hunt by scientists the world over for potential protective effects of alcohol against heart disease in women, the research has turned up virtually no evidence. Alcohol is a proven risk factor for breast cancer and is likely a cause.
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