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Researchers Question Whether American Diets Actually Work

Discussion in 'Dietetics' started by Mahmoud Abudeif, Dec 15, 2019.

  1. Mahmoud Abudeif

    Mahmoud Abudeif Golden Member

    Mar 5, 2019
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    An increasing number of Americans have tried to lose weight but, unfortunately, their waistlines have only increased, according to a recent study published in JAMA Network Open. Researchers showed that while Americans might be saying they’re attempting to lose weight, eat better, and exercise more, they likely are not doing these things. Or, if they are, they aren’t doing them well.

    For this retrospective study, researchers evaluated trends in measured BMI values and weight, self-perceived weight, self-reported attempts to lose weight, and diet strategies among US adults from 1999 to 2016. The study included data from about 48,000 people.

    The researchers assessed BMI and weight in several ways. First, through empirical observations of BMI and weight. Second, via self-reported data (ie, what participants said they weighed the year prior). And finally, by means of a comparison of self-reported weight from the year prior and observed weight. Upon analysis of all three measures, the researchers observed increasing BMI and weight trends.

    While participants’ weights and BMIs increased, so too did their attempts to lose weight, noted the researchers. During the study period, the percentage of those attempting to lose weight increased from 34.3% to 42.2%.

    Perhaps the most puzzling thing about the results is that participants appeared to be doing the right things to slim down. Strategies included:

    ● Cutting calories (21.2%, increasing to 31.9%)

    ● Exercising (18.2%, increasing to 31.5%)

    ● Drinking more water (0.2%, increasing to 26.3%)

    Study participants not only reported eating less, but paying attention to what they were eating. Researchers noted that from 2005 through 2006 and 2015 through 2016, participants reported eating more fruits and vegetables (0.1% to 29.4%) and consuming less sugar (0.2% to 20.9%). Despite their best efforts, obesity rates among Americans rose from 33.7% to 39.6% during these same time periods.

    What’s going wrong?

    The researchers suggested that these confounding results might be the product of Americans saying one thing but doing another. They noted that study participants’ perceptions of being overweight and/or obese matched reality. However, this awareness may not have translated to exercising or eating better. Interestingly, the researchers said there’s evidence that increased awareness about being overweight or obese correlates to more weight gain over time.

    According to some researchers, including the study authors, social pressure could be driving Americans to report that they’re trying to lose weight. In a previous study, 34% of study participants said they had made the attempt. However, the current study authors noted that “these findings suggest that although 34.3% to 42.2% of adults in the United States in our study reported weight loss efforts, many of them might not have actually implemented weight loss strategies or applied a minimal level of effort, which yielded unsatisfactory results.”

    It’s also likely, the researchers speculated, that although study participants decreased the quantity of food they ate, they could have been consuming the same amount of calories. This is complicated by the fact that caloric restriction for weight loss is notoriously difficult to sustain, they added.

    Study participants also reported turning to exercise in an attempt to lose weight. However, according to results from a 2008 study published in Medicine & Science in Sports & Exercise, less than 5% of US adults perform the daily recommended amount of physical activity. And these findings are in line with those from the American Heart Association, which found that 8 in 10 US adults are not performing cardiovascular and strength-training exercise at the recommended levels.

    “Decreased energy intake, adherence to reduced food consumption, and the quality of exercise are significant challenges to effective weight loss,” the researchers wrote.

    Dietary changes

    Study participants attempted to improve their diets by increasing their fruit and vegetable consumption, and by reducing their junk and fast-food consumption. However, this didn’t translate to weight loss, despite the increased trend in healthier eating. The researchers noted that these dietary improvements weren’t tracked until 2005, and that alone might be the source of the trend of improved diet without weight loss.

    They also observed that study participants mostly failed to limit fat consumption. During the 2001-2006 time frame, those who did limit fat consumption—and also exercised, took prescription weight loss drugs, or participated in weight loss programs—experienced weight loss upward of 10%.

    “Reduction of either carbohydrates or fat has been similarly related to weight loss, especially in the context of low-calorie diets,” the researchers wrote.

    Takeaways for doctors

    Throughout their research, the study authors noted that all of these weight loss methods have proven to be effective. Clearly, the problem is in implementation. Better implementation requires counseling on comprehensive, effective weight-loss strategies. These strategies should include reducing calories and exercising.

    “Notably, adherence is the primary factor associated with a successful response to a weight loss attempt,” the researchers concluded. “Therefore, weight loss strategies that consider a participant’s preferences and abilities may help to optimize participant adherence.”

    Importantly, the researchers noted that those who most need to lose weight likely do not know they need to. The inverse is true for those who do not need to lose weight; they are more likely to think they need to slim down.


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