Lesser of Two 'Evils': Fat, Sugar, Cigs

Linda Brookes, MSc


February 12, 2018

Healthcare professionals regularly see patients who should make lifestyle changes to improve their health. Despite the best advice culled from expert guidelines, however, many patients are not ready to diet, exercise, or give up smoking. And those who try are often unable to maintain the changes over the long term.

Compromise strategies that involve smaller changes may still have health benefits and encourage patients to take additional healthy steps. But compromise strategies can also carry risks. Kenneth W. Lin, MD, MPH, associate professor in the Department of Family Medicine, Georgetown University School of Medicine, and staff physician at MedStar Health Center, Family Medicine at Spring Valley, Washington, DC, discussed with Medscape how some of these strategies might help, even when unsupported by evidence, whereas others might be as harmful as the original risk factor.

Low-Fat Versus Low-Carb Diets

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Many people who want to lose weight try "fad" diets that involve drastically reducing consumption of one food type (macronutrient) and replacing it with another. In the 1960s, low-fat diets, as initially recommended by the American Heart Association,[1] became popular, a trend encouraged by the sugar industry.[2] Low-fat diets are still popular, despite evidence from randomized trials indicating that low-fat diets are no more successful than other diets.[3,4] The low-fat diet is also associated with high carbohydrate consumption, which has been linked with increased mortality risk.[5] More recently, low-carbohydrate/high-protein diets, such as the Atkins diet, have also been widely adopted, having shown short- and long-term benefits in weight loss in clinical trials, although they were also associated with increases in low-density lipoprotein (LDL) cholesterol.[6] However, whichever macronutrient patients decide to focus on, adherence to any of these diets is poor.

"I'm awfully suspicious of the whole paradigm of these different diets," Dr Lin says. "A [traditional] Mediterranean diet or the DASH (Dietary Approaches to Stop Hypertension) diet are the ones that I usually talk about with patients. It's pointless to focus on how much fat is in a food, especially when it is labeled as 'low-fat' and there is no particular reason for fat to be in it in the first place." Dr Lin notes that dietary guidelines now concentrate on restricting intake of saturated and trans fats rather than all fats.[7] The Mediterranean diet is more likely to contain poly- and monounsaturated fats, the so-called "good" fats, he points out.

Verdict: A balanced diet is preferable to any macronutrient-focused diet.

Sugar Versus Artificial Sweeteners

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Current dietary guidelines recommend that consumption of added sugars (ie, sugars in processed and prepared foods) should not exceed 10% of total daily calories (equivalent to 50 g/day, or 200 kcal of a 2000 kcal/day diet),[7] a limit that is exceeded by most of the population.[8] Beverages—mostly sodas, energy and sports drinks, and flavored waters—account for almost one half (47%) of added sugars consumed.[7]

Artificial sweeteners are an attractive dietary alternative to sugar. "In the case of sodas, I would rather you didn't drink them at all, but if you are going to drink soda, at least we can take the calories out of it," Dr Lin comments, adding, "For an artificial food, such as a soda, I have no problem advising patients to drink the diet version instead."

The popularity of artificially sweetened foods and beverages (consumed by 25% of children and > 41% of adults[9]) has raised concerns about adverse health effects, but studies looking for increased risks for cancer, diabetes, or dental caries, for example, have all been inconclusive.[10,11] Another potential effect may be a compensatory increase in sugar intake from other sources to satisfy the craving for sweetness. "That's a potential drawback, but I doubt that anyone would eat enough to completely compensate for all the sugar they are getting rid of with artificial sweeteners," Dr Lin suggests. "So even with some compensation, artificial sweeteners are helpful, at least in terms of calorie reduction."

Verdict: Artificial sweeteners help weight loss/maintenance.

Weight Cycling Versus Stable Overweight

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"Fad" diets often lead to weight cycling (the "yo-yo effect"), when dieters repeatedly fail to stick to their diets and rapidly regain any weight lost (and sometimes gain more) after they resume normal eating.[12] Recent consumer literature suggests that weight cycling may be more detrimental than maintaining a stable excess amount of body weight and that it may be possible to be "fat and fit."

Whether it's possible to be metabolically healthy (ie, no hypertension, glucose abnormalities, or dyslipidemia) while overweight or obese is controversial. People with metabolic syndrome have shown an increased risk for cardiovascular events and death over the long term (> 10 years), regardless of their weight, compared with metabolically healthy people of normal weight, implying that risks are similar in normal-weight and overweight people without metabolic syndrome.[13] In contrast, metabolically healthy overweight and obese individuals have been found to be at higher risk for coronary heart disease compared with their normal-weight counterparts.[14] Other studies suggest that overweight or obese people differ in adiposity and muscularity, and that some may be physically fit and may not need to lose weight.[15]

Although weight cycling hasn't been firmly linked to an increased risk for such chronic conditions as heart disease, diabetes, fractures, or depression, overall there is little evidence of adverse effects.[16,17] "Within a certain range—about 20 lb—if you lose that weight and then gain it back, that is probably better than stable overweight," Dr Lin proposes. "The type of weight cycling that may be more harmful occurs when people go on crash diets, almost stop eating, and lose about 50 lb, and then regain all the weight when they start to eat normally again," he suggests. "Even if you are losing weight with theoretically sustainable habits, such as exercise and moderation in eating, you can still expect some weight cycling because nobody is perfect. A fairly sustained effort with just a few lapses is probably better than stable overweight," Dr Lin maintains.

Verdict: Low-level weight cycling is better than stable overweight.


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