|What Really Works in Fighting Obesity?
Len Kravitz, Ph.D.
Casazza, K., Fontaine, K.R., Astrup, A., Birch, L.L., Brown, A.W. et al. (2013). Myths, presumptions and facts about Obesity. The New England Journal of Medicine, 368(5), 446-454.
Many exercise professionals have some strong opinions and beliefs about the efficacy and health consequences of obesity and how it can best be managed and/or prevented. Casazza et al. (2013) recently researched several common and popular views on obesity in an effort to bring clarity and accuracy to what science has elucidated about several of these particular topics. The scientists note that adhering to some traditional viewpoints on obesity management may be unsafe and clinically obstructive for a client. The authors explain that with obesity myths there is strong scientific data that contradicts the commonly held standpoint. Presumptions are accepted beliefs in the absence of supporting science. Several of these myths and presumptions are discussed in this column, with the best available evidence presented for both. Side Bar 1 addresses some central facts about obesity that are documented in the literature.
Myth 1. To Attain Desirable Losses in Overweight/Obesity A Client Needs to Just Make Small Lifestyle Changes.
For any lifestyle modification, small changes are a great way to begin. However, Casazza and colleagues explain that the evidence indicates changes in body composition in response to changes in energy intake and expenditure (via physical activity) have a varying degree of weight loss for each person, with much individual variability exists. As well, changes in energy intake and output often result in physiological compensatory adjustments that inhibit continual weight loss. Personal trainers need to educate clients that due to these potential changes clients may readily need to make even greater changes in energy input and output for continual positive gains to continue.
Myth 2. Setting Realistic Goals is the Best Approach to Successful Weight Loss
Although genuine goal setting has always been a steadfast rule of behavior change models, Casazza et al. highlight that the research doesn't show any negative outcomes from clients having more ambitious weight loss goals and their attainment of these goals. In fact, the authors note that several studies indicate that more robust goal setting with weight loss may result in even better than expected outcomes.
Myth 3. Rapid Weight Loss is Associated with Poor Weight-Loss Outcomes
Casazza et al. summarize that some studies show that rapid initial weight loss (via low-energy diets) may actually be favorable for long-term outcomes in some overweight persons. One fear with this approach has always been that if a person loses weight too fast they will gain it back just as quickly. The authors note that many over overweight people tend to have meaningful early weight loss success, which they are able to ultimately sustain. However, a major concern with rapid weight loss strategies is that the person is eating a nutritionally inadequate very-low-calorie diet, which definitely poses problematic health consequences in the long term.
Myth 4. A Peron's Readiness for Change is Associated With Their Weight Loss Success
Several behavior change models suggest a person's readiness to change a behavior is crucial for a person to make the necessary life-long weight loss adjustments in their lifestyle. Casazza and colleagues cite five rather large trials with approximately 3,910 participants that indicate people 'willing' to enter into a weight-loss program are going to attain some degree of weight loss, regardless of where they are on in their readiness to change behavior model. The authors' highlight that readiness to change is not always a predictor of weight loss attained or program adherence.
Myth 5. Breast-Feeding is Protective of Obesity
Many exercise professionals are familiar with this century-old conjecture suggesting breast-fed infants are less likely to be obese later in life. Casazza and colleagues argue that better controlled studies that have followed children for more than 6 years do not show persuasive evidence of an anti-obesity effect from breast-feeding. The authors note that even though breast-feeding may not have a shielding effect on childhood obesity, several advantageous health benefits have been identified for the infant, and thus breast-feeding should be encouraged.
Presumption 1. Regularly Eating Breakfast (versus skipping breakfast) Guards Against Obesity
The presumption is that people who skip breakfast tend to over eat later in the day. Casazza et al. note that a person's lifestyle habits, whether they are accustomed to eating breakfast (versus skipping breakfast), is a major determinate with this presumption. Thus, although the importance of eating after a night's sleep is quite profound from a standpoint of energy and nutrient replenishment, any weight-gain effects from skipping breakfast are more associated with the established eating habits of the person.
Presumption 2: Early Childhood Exercise and Eating Habits Influence Weight Throughout a Person's Life
It is presumed that early childhood is the period in which people learn eating and exercise habits that will influence these behaviors throughout life. Casazza and colleagues note that no randomized, controlled trials have been completed on this presumption. However, they suggest that eating behaviors may be more a function of genetics rather than learning.
Presumption 3. Eating More Fruits and Vegetables Will Result in More Weight Loss and Less Weight Gain
Clearly the intake of fruits and vegetables has credible scientific merit for improved health and disease prevention. However, this presumption about eating more fruits and vegetables postulates that people eat less of other foods and thus a reduction in calories. Currently there is no research to support or reject this presumption.
Presumption 4. Yo-Yo Dieting (Weight Cycling) is Associated with Increased Mortality
This presumption is based on observational studies, which show people with stable weight have lower mortality rates than those with weight instability (i.e., cycling). More investigation is needed to resolve this question.
Presumption 5. Snacking Triggers Weight Gain and Obesity
It is alleged that eating snacks interfere with the amount of food eaten in subsequent meals, leading to weight gain. Casazza and colleagues report that randomized, controlled studies, as well as observational research have not shown this to be true.
Rethinking Traditional Viewpoints
From this inclusive review of the literature, Casazza and colleagues clearly offer some resounding evidence-based statements that challenge many beliefs about obesity and weight loss. As an industry we need to always conscientiously evaluate unproven strategies and interventions in order to offer our students and clients the best knowledge and guidance possible.
Side Bar 1. The Facts of Obesity
The following facts of obesity presented by Casazza et al. are well supported by scientific evidence and offer helpful practical application for personal trainers.
1. Meal replacement products have been shown to promote greater weight loss. It appears these products provide needed structure and regimen with calorie intake that positively enhances weight loss interventions.
2. Heredity is not a destiny to overweight and obesity. Genetic factors do play a role in weight gain; however, consistent environmental changes in energy intake and energy output have been shown to be central for the reduction in body weight and obesity prevention.
3. Regardless of body weight, an increase in the level of fitness has encouraging health benefits. Many of the deleterious health effects of obesity are lessened with consistent exercise.
4. Encouraging a client to go on a diet does not work well in the long-term. Diets effectively reduce weight, but they generally do not work well in the long-term (Donnelly et al., 2009). An overall sustainable lifestyle change with a lowered energy intake and increased energy output will result in supportable weight loss goals and weight regain prevention much better than a diet.
5. Exercise in sufficient doses is a critical component of a successful weight loss program. There must be substantial amount of exercise for successful weight loss and weight regain prevention. ACSM recommends accumulating 250 to 300 minutes/week (~2,000 kilocalories/week) of moderate-intensity exercise for weight loss and prevention of weight gain (Donnelly et al., 2009).
6. Continuation of conditions that promote weight loss also promotes weight maintenance. Weight regain prevention is an ongoing challenge that requires sustainable efforts of energy output and portion control on energy input.
7. With overweight children, programs that involve parental support in a home setting have the best results. This in no way devalues school, agency and organization efforts to promote weight loss with youth. It merely shows the importance of the home setting for sustainable weight loss interventions with youth.
8. There are a few pharmaceutical agents that help overweight clients lose weight. Moderately effective medical treatments are available as prescribed and administered by clinical professionals.
9. For severely obese persons bariatric surgery results in successful weight loss results. In addition, there is a reduction in the incidence of diabetes and mortality as well with bariatric surgery.
Donnelly, J. E., Blair, S. N., Jakicic, J. M., Manore, M. M., et al. (2009). Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Medicine & Science in Sports & Exercise, 41(2), 459-469.
Len Kravitz, PhD, is the program coordinator of exercise science and a researcher at the University of New Mexico, Albuquerque, where he won the Outstanding Teacher of the Year award. He has received the prestigious Can-Fit-Pro Lifetime Achievement Award and American Council on Exercise Fitness Educator of the Year.