The Facts on Fad Diets

A shortcut to obesity?

By Eva Chanda

In 400 BC, when the first ancient Greek asked, “Does this toga make my butt look fat?” the iconic physician Hippocrates advised eating in moderation, along with taking oily foods as laxatives, having seawater enemas, vomiting after lunch, and exercising naked. Are today’s diet crazes any better?

How can you spot a fad diet? They typically promise dramatic weight loss in a short time (over 1 kg per week) by banning one or more foods, while touting others as having exaggerated benefits. Many require buying pricey diet foods, supplements or memberships, and some are outright frauds: nearly 55 percent of weight-loss ads make at least one false claim.

Lisa Rutledge, a dietitian with the McGill Cardiovascular Health Improvement Program in Montreal, sums up fad diets like this: “By going on crazy diets, starving themselves, or having “yo-yo” weight fluctuations, chances are you’ll gain weight in the long run, because restricting calories will slow down your metabolism. That’s scarier than being overweight.”

Low-carb: Dr. Robert Atkins is credited — or blamed — for unleashing this diet craze in the 1990s, but the first published version actually came out in 1825, by influential French foodie Jean Brillat-Savarin. The diet comes in many guises, but the basic plan is “carbs bad, meat good”: cut carbohydrates, such as grains, potatoes, starchy vegetables and fruit, to around 20 percent of total calories, but eat more meats and fats. Downsides include constipation from lack of fibre (it’s a carb) and nutrient shortages. Drastically cutting carbs can trigger ketosis from the body burning fat, which sounds great, but has side effects of nausea, headache, mental fatigue and bad breath.

Tapeworms: This madness struck at the turn of the 20th century. Victims would swallow beef tapeworm cysts, and the pounds would melt off as the creatures relentlessly grew and sucked up food in the intestines. Win-win, if you don’t mind carrying around a three-metre-long parasite and risking diarrhea, vomiting and abdominal pain — and the tapeworm could escape and end up in your brain, causing headaches, eye problems, meningitis, epilepsy and dementia. Today, it’s illegal to import or market tapeworms in Canada, but the fad has reared its ugly head again in Hong Kong and Mexico.

Grapefruit: A perennial favourite, this fad diet dates to the 1930s and was based on the theory that grapefruit contains a fat-burning enzyme (it doesn’t). It involved nibbling on a few vegetables, a bit of protein and a grapefruit at every meal for three weeks. At only 800 calories a day, grapefruit or no grapefruit, dieters were bound to lose weight, but they would usually find it again soon enough.

Beer diet: Especially for the guys, there’s the beer diet — pretty self-explanatory, it’s just beer. One blogger recently wrote about his 46-day “beer fast” for Lent: he drank four or five 288-calorie “doppelbock” beers a day and lost 25 pounds, but since beer contains no protein, he also developed symptoms of kidney damage, from the body digesting its own muscle — bye-bye six-pack abs!

 

The ABCs of BMI
So when does “a few extra pounds” become a medical concern? The body mass index (BMI) is used to size up adults based on height versus weight BMI charts or determined using online BMI calculators. BMI is calculated differently in youths aged 2 to 20; each child’s BMI is compared to a chart of BMI data from a large population of children of the same sex and age, bracketed into underweight, healthy weight, overweight and obese categories.

BMI gauges risk for diseases linked to higher body fat, such as heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems and certain cancers. But it’s not perfect: since muscle weighs more than fat, BMI can overestimate body fat in muscular people and underestimate it in seniors and others who’ve lost muscle. Dietitian Lisa Rutledge adds, “Weight is not the only thing determining your health — smoking, eating unhealthily and, especially, being inactive may have a bigger health impact. Being large is not a death sentence. Eating a bit healthier and moving around a bit more is better than going on a radical diet.”

Measuring waist circumference (WC) seems to be better at flagging higher risk of diabetes, heart disease, stroke and high blood pressure than BMI. Carrying more fat around your waist, described as apple-shaped, puts you at higher risk than if you’re more pear-shaped, with extra fat on your hips and thighs. For most people, a WC at or above 102 cm (40 in.) for men, and 88 cm (35 in.) for women, is considered higher risk.

Summer 2013, Vol 5 N°3

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