I’m sure I’m not the only health professional that bites their tongue whenever a patient starts a question with “I heard on Dr. Oz that…” More often than not, I have expectations to realign, and some assumptions to correct. I could easily devote all my posts to simply correcting information presented on the Dr. Oz show. But given I’m blogging here biweekly, and Dr. Oz has a daily television show, I’ll never be able to catch up. So while my first choice in topics isn’t to add a post to our extensive Dr. Oz archives, I often end up, like many other health professionals, needing to respond to his shows shortly after they air.
Should you happen to be someone that has never seen the Dr. Oz show, Dr. Mehmet Oz is an Oprah protégé who has gone on to build a health media empire that is possibly the biggest vehicle for health pseudoscience and medical quackery on television. Whether it’s promoting homeopathy, recommending unproven supplements, or advocating ridiculous diet plans, there seems to be no health subject too dubious to endorse. Oz has established an impressive track record of providing highly questionable health advice. A few months ago I examined his absurd endorsement of green coffee beans, followed by his dubious “clinical trial” of green coffee beans that likely didn’t meet minimal research ethics standards. Then there was the weight loss “miracle” (his words), red palm oil, which followed the same episodic formula of breathless hyperbole backed by questionable evidence. One of the meta-trends of the Dr. Oz show are weight loss secrets – typically gimmicky interventions, supplements and therapies that he promotes as panaceas for obesity.
What frustrates me the most about Dr. Oz is that he should know better. He’s a heart surgeon, (who continues to treat patients), an academic, and a research scientist, with literally hundreds of publications to his name. He has gone through the peer review process more times than most health professionals. There is little reason to expect, based on his pre-television history, that he’d be willing to build a platform to offer demonstrably bad health advice. And that’s a shame, because with a show in 118 countries that reaches over 3 million viewers in the USA alone, it could be a powerful tool for providing good health information to those seeking it. And more often than not, that opportunity is squandered.
Another meta-trend on The Dr. Oz Show is the list. (Actually that’s not just Dr. Oz, it’s more of an internet trend, with websites like Cracked solely devoted to lists.) Sure it’s linkbait, but it works, and these lists of health-related topics are shared via social media. So if this list didn’t already appear on you Facebook wall, you may see it soon, titled Eat Yourself Skinny!
It may seem too good to be true, but the key to weight loss is right in your grocery store. These 15 superfoods can rev your metabolism, whittle your waist and leave you looking and feeling better than ever.
– Dr. Oz
Superfoods. I both love and hate the term. I’ll put my business degree hat on first. It’s genius. Who has time for perfectly adequate foods, or even good food? Superfoods are what you need to be consuming. Can’t you just picture yourself fitter, happier and more virtuous? The pseudoscientific bookends to vitamins and supplements, superfoods are touted as the simple dietary cure. The real genius of the term is that it has no established definition. Here, superfoods are products that “rev” your metabolism and “whittle” your waist. The implication is clear – consuming them will have magical effects – you eat, you still lose weight, and you look and feel wonderful. What could be wrong with foods like that?
So now I’ll put my pharmacist hat on. Superfoods are pure marketing speak, meaningless nutrition woo like “detox”, “clease”, “immune boost” and pretty much every other word you’ll see in the advertising from a naturopath or nutritionist. Claims are usually based on anecdotal information, or information extrapolated far beyond the scientific evidence. Rather than help dietary decisions, designing what you eat based on “superfoods” can make meal planning more complex, with consumers focusing on single ingredients rather than overall dietary choices. There’s a fad component too. Pomegranates and acai berries were superfoods, but now they’re out. We can only eat so much food in one day, and superfoods are a compelling term used to shape our food purchasing decisions.
So with this in mind, let’s take a look at Dr. Oz’s list of superfoods, and his claim that they are the “key to weight loss”:
Dr. Oz claims: “Ignites your fat-burning furnace”, 50% of calories are not absorbed, reduce blood sugar, “may burn fat faster”
Reality check: There’s no clear evidence that establishes bean consumption will cause you to preferentially “burn fat”, though they may help with controlling blood sugar. Oz is partially correct with respect to his calorie counts, as the usual 4 calories/gram of sugar rule isn’t accurate when it comes to fiber. But it’s only these calories that are overestimated, not the entire calorie count for the food. Still it’s hard to argue with increasing your consumption of beans which are nutrient-packed, high in protein, and low in fat. Whether they promote weight loss, however, hasn’t been established.
#2: Pine nuts
Dr. Oz claims: “Help suppress hunger”; contain pinolenic acid, which in a clinical trial “was associated with a reduction in food intake by 36%”.
Reality check: Pine nuts (which are actually seeds) are delicious, but they’re also calorie-rich, owing to their fat content. (A tablespoonful of pine nuts provides 60 calories). I could locate no published clinical trials that have studied pine nuts directly. The “36% reduction in food consumption” claim seems to come from an paper presented at the American Chemical Society National Meeting that used daily doses of 3 grams of pinolenic acid (supplied as the oil) in 18 overweight volunteers. It does not appear to have been published, peer reviewed, or duplicated. Given pine nuts are usually consumed as part of a meal, and not as a pre-meal supplement of the oil alone, it’s difficult to see how relevant this research is to everyday weight management.
#3. Fennel tea
Dr. Oz claims: “Cleansing”, “boosts digestion”, “resets taste buds”, reduces fat storage, “squash morning hunger pangs”
Reality check: There is no credible evidence demonstrating that fennel can do any of these things. Like many herbal remedies, side effects have not been systematically studied, but it’s generally considered safe when consumed as a food. While it’s most popular for promoting lactation, its effects have not been established, and is also considered potentially unsafe for that use.
#4. Crimini mushrooms
Dr. Oz claims: Meaty flavour cuts the fat when mixed in meat-based dishes.
Reality check: I can’t argue with Dr. Oz here. Crimini mushrooms are tiny portobellos. If you like mushrooms and want a meat substitute, mushrooms are a reasonable alternative. Nothing super about them, but they are low-calorie and nutritious.
Dr. Oz claims: When eaten pre-meal, the pectin reduces the subsequent sugar and calories that are absorbed into the bloodstream.
Reality check: Apples are delicious and most varieties are reasonably low in calories. Pectin is a soluble fibre that gives a gelatinous consistency to products like jams and jellies. I could find no published information that demonstrates that apple or pectin consumption reduces subsequent calorie absorption, though there is some evidence suggesting pectin supplements can have beneficial effects on cholesterol levels.
Dr. Oz claims: The monounsaturated fats are “are healthy sources of energy to keep you going all day long.”
Reality check: Avocados are a great source of monounsaturated fats and that seems to have positive cholesterol effects. They are a source of energy – quite a bit of it, with about 300-400 calories each. As a source of nutrition they’re an excellent part of your diet, as long as you keep in mind the total calories.
#7. Raspberry ketone
Dr. Oz claims: This product regulates adiponectin, a protein that causes “the fat within your cells to get broken up more effectively, helping your body burn fat faster.”
Reality check: Come on Mehmet. You were doing reasonably well, only to veer off into rank pseudoscience with your favorite “miracle fat-burner in a bottle”. Setting aside the fact that raspberry ketone isn’t really a “food” at all (it’s formulated synthetically), the scientific evidence doesn’t back up these claims. There are no human studies that substantiate these statements. It’s supplement snake oil.
#8. Chili peppers
Dr. Oz claims: Capsaicin “curbs your appetite while you eat” and “raises your body temperature, which may boost your metabolism.”
Reality check: Oz is suggesting that chili peppers will independently change the heat production of your body, confusing capsaicin’s effects on pain receptors on tongues, for actual thermal energy. There is the hypothesis that capsaicin supplements may have some effects on calorie burn, but it’s not clear that the modest increase is the same as eating chili peppers as part of a typical diet. Chili peppers are delicious though, so if you like them, go ahead and eat them – just don’t expect that hot sensation to mean you’re burning away calories.
Dr. Oz claims: “Slow the absorption of carbohydrates” and “slows the passage of food through your stomach, keeping you fuller for longer.”
Reality check: Vinegar is an old folk remedy, its main ingredient is acetic acid (the usual home supply version is 4-8% acetic acid in water). The best evidence I could find to substantiate Oz’s claim of satiety was a study in 12 people given white bread and vinegar. As an unblinded study, not much can be concluded. There’s also a small study suggesting vinegar may enhance insulin sensitivity. So while there’s no evidence to suggest it will “rev up” your metabolism or aid in weight loss, if you like the taste of vinegar or pickled foods, enjoy. Just don’t expect you’re losing weight doing so.
Dr. Oz claims: “Slows the passage of food through your stomach” and “lowers your blood sugar levels by stimulating glucose metabolism.”
Reality check: Cinnamon supplements have been studied in diabetics and beneficial effects have not been established. There is no evidence to demonstrate that cinnamon has any beneficial effects on weight in people with or without diabetes. If you like it, eat it. But cinnamon won’t negate the calories you’re eating it with.
#11: Chia seeds
Dr. Oz claims: The soluble fiber has “cholesterol-lowering properties and prevents the absorption of fat”
Reality check: Chia is an herb, eaten for its seeds, which are a good source of fiber and the omega-3 fatty acid, alpha-linolenic acid. A single-blind study showed chia had no effect on weight loss, though it may improve some risk factors, like cholesterol, in those with diabetes. Given alpha-linolenic acid is poorly converted to docosahexaenoic acid (DHA), if you’re looking for cardiovascular benefits you’re better off getting DHA directly via cold water fatty fish. So while chia is a reasonable addition to your diet, there is no evidence it has any special ability to support weight loss.
#12: Green tea
Dr. Oz claims: Contains EGCG (epigallocatechin gallate) that “increases the hormone responsible for making you feel satiated”; “can help prevent storage of excess fat”, “improve your appetite-regulating hormones” and will change how your body handles cravings and metabolizes food.
Reality check: Green tea is brewed from the non-fermented leaves of the Camellia sinensis plant. It contains a number of biologically active ingredients which are believed (though not established) to be a panacea for nearly everything. With respect to weight loss, a systematic review of green tea for obesity concluded that green tea has no meaningful effects, and a Cochrane review concluded that any effects are “not likely to be clinically important”.
#13. Pepitas (pumpkin/squash seeds)
Dr. Oz claims: “Seeds have been shown to decrease the body’s ability to store fat”; the protein and magnesium “helps curb cravings and strengthen muscles”; “Eat 1 cup of seeds a few times a week.”
Reality check: Pumpkin seeds, like other seeds, are nutrient and energy dense. One cup of pumpkin seeds has about 700 calories, which is about the same as a Double Big Mac (albeit with less fat and more fiber). Three cups of seeds a week could easily exceed an entire days’ worth of calories. There is no published evidence to suggest that seeds block fat production or retention in any meaningful way that could assist with weight loss or weight maintenance.
#14. Red lentils
Dr. Oz claims: “these legumes will help you stay fuller for longer.”
Reality check: Hard to find fault with lentils which are both nutritious and high in fiber which might contribute to satiety. While no “superfood”, they are a staple in many diets – I prefer mine as daal.
Dr. Oz claims: “Women who ate water-rich foods lost 33% more weight in the first 6 months than women on a low-fat diet”; contains vitamins A, C, “as well as the ‘mother of all antioxidants,’ glutathione, which is known to help strengthen the immune system.”
Reality check: For a fruit that’s so delicious and is mainly water, watermelon has a lot of nutrients too. The study referred to is this paper which compared a low-fat diet to a low-fat diet with more fruits and vegetables. The group randomized to fruits and vegetables lost about 5lbs more than the other, an increase of 33% at the six month mark (the difference narrowed by one year). So while the study is reported accurately, it is not a trial that studied watermelon, or that studied the effect of fruits and vegetables alone.
Oz’s latest list is a mix of both reasonable and silly dietary advice that repeatedly overstates the evidence, while ignoring the biggest determinant for obesity: calorie consumption. The list reinforces the rule that information presented on the Dr. Oz show cannot be taken at face value.