Dr. N. John Bosomworth (biography, no disclosures)
What I did before
During 40 years of practice, one of the most frequent concerns voiced by otherwise healthy patients was the desire to lose weight. I respected this concern and calculated the “ideal” weight using the American Diabetic Association tables. We would then discuss the need for a reduced calorie low fat diet, and I might refer if a dietitian was available. Since 1961 the American Heart Association had suggested a diet low in cholesterol and saturated fat (1), and this was incorporated into Dietary Guidelines for Americans in 1980, with an upper limit of 30% of total calories to be derived from fat (2).
In addition, we discussed the possibility of a gradually increased walking program, aiming for 2 miles at a moderate pace at least 5 days per week (this was when Canada was just beginning to go metric). I had embraced the teaching of leading physical activity researchers at the time: “What happens to what we eat depends on whether we exercise enough or not” (3). As it happens, this prescription was reasonably close to current WHO recommendations (4). Weight loss was rarely maintained.
What changed my practice
By the 1980’s reduced dietary fat had been replaced by increased refined carbohydrate (2), and evolving technologies, including the personal computer, had reduced physical activity (5,6). This was a perfect storm for energy accumulation, and it coincided with accelerating overweight and obesity (7). Several issues have become more clear in the last 35 years:
- There is no evidence for benefit of weight loss in healthy people. Optimum weight to minimize mortality is in the high normal or overweight range (8,9). Except for class II and III obesity (BMI 35.0 to 39.9 and BMI equal to or greater than 40.0), intentional weight loss is associated with increased mortality in most observational studies (10,11) unless there is obesity associated co-morbidity (12). The safest body size trajectory in healthy people is a stable weight (9). Age adjusted BMI: BMI is a poor surrogate to predict mortality. This is especially true in the elderly. Observational studies suggest that mortality is lowest in overweight and class I obese elderly, and weight trajectory trends to a loss of 0.5 kg/year on average. Mortality is increased if weight loss is unintentional, weight loss exceeds 5%, or BMI falls below 22 in the elderly. Continued exercise benefits by preserving muscle mass and helping prevent “frailty” (41, 42).
- We were wrong about dietary fat. While it is relatively calorie dense, there is no evidence that saturated fat contributes excessively to cardiovascular disease (13,2). Restricted fat was replaced in the food supply by increased refined grains and added sugars, along with reduction of potentially beneficial fatty acids (2). Level 1 evidence suggests that a Mediterranean diet pattern reduces cardiac risk factors and mortality as compared to a low fat diet. (14,15,16,17). The US Dept. of Health Dietary Guidelines for Americans (18) and the AHA guidelines on lifestyle management (19) emphasize dietary pattern change rather than specific nutrient or calorie restriction. Weight loss can result, but it is really only a surrogate for successful lifestyle change.
- It takes a modest amount of exercise to attain good metabolic benefit. Meta-analyses of prospective cohort exercise studies uniformly show benefit for prevention of cardiovascular disease (16,20) and mortality (21,22,23,24). The largest derived benefit is progression from sedentary to low levels of exercise. One prospective cohort following 416,000 people over 8 years showed a 14% mortality reduction with as little as 15 minutes of moderate activity daily (25).
- It takes a lot of exercise to achieve weight loss. While the recommended 30 minutes 5 days/week is sufficient for metabolic benefit (3), it requires 45-60 minutes per day of brisk walking to prevent ongoing weight gain using exercise alone (26,27). Weight loss would require additional activity. Since the body is well designed to defend its initial weight, the reduced obese must engage in 60-90 minutes per day of moderate activity to prevent regain (26,28). Further, this activity has to be maintained indefinitely. While it is clearly possible to lose and maintain weight using exercise alone, it is also clear that it is very difficult to actually outrun a bad diet (29).
What I would do now
I would initially explore the reasons for the desire to lose weight:
- Does this person have an alarm symptom such as “indigestion” which may have suddenly prompted a decision to lose weight or begin exercise? This requires a focused history with cardiovascular risk evaluation to reduce the prospect of an unfit individual at high risk undertaking a sudden increase in activity.
- Does this person seek improved health through reduction of cardiovascular and metabolic risk? This could be achieved with minimal or no weight loss by increase in physical activity (30,31). Without calorie restriction, 45-60 minutes of moderate exercise per day would be required to avoid ongoing weight gain. A Mediterranean or DASH (Dietary Approaches to Stop Hypertension) dietary style would contribute additional benefit. These measures could stabilize weight, which would otherwise increase by 0.25-0.50 kg./year (8).
- Does this person seek to improve quality of life? This is a feature of the Mediterranean diet, which can produce benefit without weight loss (32). Quality of life has a direct association with increased exercise in a systematic review (33), and this benefit is independent of weight change (34,35).
- Is the wish for weight loss simply cosmetic? Between 12-20% of people intending to lose weight are able to reduce by 10% for over 1 year (36,37). Along with the change in eating pattern, this decision can involve 60-90 minutes per day of moderate exercise to maintain that weight loss without significant calorie restriction, above 60-90 min/day moderate exercise for weight loss. Available data suggest that lifestyle measures would have to continue indefinitely to prevent rapid regain (27).
I would encourage a Mediterranean or DASH style eating pattern to minimize the influence of the added sugars and refined carbohydrates dominating our current obesogenic environment. If the patient was unable to progress to 45-60 minutes per day of moderate exercise to prevent ongoing weight gain, we would have to discuss calorie restriction. If there was still a desire for weight loss after discussion of the association with increased mortality, it would be necessary to increase the caloric deficit and further increase exercise. I would warn the patient that this could be a difficult process, as the body will defend its current weight through an increase in hunger and a disinclination to exercise (38), however any mortality risk incurred by weight loss could be tempered by long-term maintenance of physical activity (39,40). The safest option would be weight stability and optimizing fitness at any weight.
- Central Committee for Medical and Community Program of the American Heart Association ad hoc committee on dietary fat and atherosclerosis. Dietary fat and I ts relation to heart attacks and strokes. Circulation 1961; 23: 133-136. (View)
- Mozaffarian D. The 2015 US Dietary Guidelines: Lifting the ban on total dietary fat. JAMA 2015: 313(24): 2421-2422. (Request with CPSBC or view UBC)
- Paffenbarger RS Jr, Blair SN, Lee IM, Hyde RT. Measurement of physical activity to assess health effects in free-living populations. Med Sci Sports Exerc.1993; 25(1): 60-70. (Request with CPSBC or view UBC)
- Global Recommendations on Physical Activity for Health. Geneva: World Health Organization [Online]; 2010. Accessed Aug 4, 2015. (View)
- McGinnis JM The public health burden of a sedentary lifestyle. Med Sci Sports Exerc. 1992; 24 (suppl 6); S196-S200. (Request with CPSBC or view UBC)
- Siegel PZ, Brackbill EM, Frazier EL, Marolis P, Sanderson LM, Waller MN. Behavioural risk factor surveillance 1986-1990. MMWR Morbid Mortal Wkly Rep. MMWR Surveillance Summaries 1991; 40 (SS-4): 1-23. (Request with CPSBC)
- Lewis CE, Smith DE, Wallace DD, Williams OD, Bild DE, Jacobs DR Jr. Seven-year trends in body weight and associations with lifestyle and behavioral characteristics in black and white young adults: the CARDIA study. Am J Public Health. 1997; 87(4): 635-642. (View with CPSBC or UBC)
- Orpana HM, Tremblay MS, Fines P. Trends in weight change among Canadian adults: evidence from the 1996/1997 to 2004/2005 National Population Health Survey [Online]. Accessed July 4, 2015. (View)
- Strandberg TE, Strandberg AY, Salomaa VV, Pitkälä KH, Tilvis RS, et al. Explaining the obesity paradox: cardiovascular risk, weight change, and mortality during long-term follow-up in men. European Heart Journal 2009; 30: 1720–1727. (View)
- Harrington M, Gibson S, Cottrell RC. A review and meta-analysis of the effect of weight loss on all-cause mortality risk. Nutr Res Rev. 2009; 22(1): 93-108. (View)
- Klenk J, Rapp K, Ulmer H, Concin H, Nagel G. Changes of body mass index in relation to mortality: results of a cohort of 42,099 adults. PLoS One. 2014; 9(1): e84817. (View)
- Kritchevsky SB, Beavers KM, Miller ME, Shea MK, Houston DK, Kitzman DW, et al. Intentional weight loss and all-cause mortality: a meta-analysis of randomized clinical trials. PLoS One. 2015; 10(3): e0121993. (View)
- Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010; 91(3): 535-546. (View)
- Nordmann AJ, Suter-Zimmermann K, Bucher HC, Shai I, Tuttle KR, Estruch R, et al. Meta-analysis comparing Mediterranean to low-fat diets for modification of cardiovascular risk factors. Am J Med. 2011; 124(9): 841-851. (View with CPSBC or UBC)
- Kastorini CM, Milionis HJ, Esposito K, Giugliano D, Goudevenos JA, Panagiotakos DB. The effect of Mediterranean diet on metabolic syndrome and its components: a meta-analysis of 50 studies and 534,906 individuals. J Am Coll Cardiol. 2011; 57(11) :1299-1313. (View)
- Sofi F, Abbate R, Gensini GF, Casini A. Accruing evidence on benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis. Am J Clin Nutr. 2010; 92(5): 1189-1196. (View)
- Rees K, Hartley L, Flowers N, Clarke A, Hooper L, Thorogood M, Stranges S. ‘Mediterranean’ dietary pattern for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2013; 8: CD009825. (View with CPSBC or UBC)
- US Department of Agriculture. Scientific report of the 2015 Dietary Guidelines Advisory Committee [Online]. Accessed Aug. 8, 2015. (View)
- Eckel RH, Jakicic JM, Ard JD, de Jesus JM, Houston Miller N, et al. American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014; 63(25 Pt B): 2960-2984. (View with CPSBC or UBC)
- Sattelmair J, Pertman J, Ding EL, Kohl HW 3rd, Haskell W, Lee IM. Dose response between physical activity and risk of coronary heart disease: a meta-analysis. Circulation. 2011; 124(7): 789-795. (View with CPSBC or UBC)
- Samitz G, Egger M, Zwahlen M. Domains of physical activity and all-cause mortality: systematic review and dose-response meta-analysis of cohort studies. Int J Epidemiol. 2011; 40(5): 1382-1400. (View)
- Hamer M, Stamatakis E. Metabolically healthy obesity and risk of all-cause and cardiovascular disease mortality. J Clin Endocrinol Metab. 2012; 97(7): 2482-2488. (View with CPSBC or UBC)
- Nocon M, Hiemann T, Müller-Riemenschneider F, Thalau F, Roll S, Willich SN. Association of physical activity with all-cause and cardiovascular mortality: a systematic review and meta-analysis. Eur J Cardiovasc Prev Rehabil. 2008; 15(3): 239-246. (Request with CPSBC or view UBC)
- Löllgen H, Böckenhoff A, Knapp G. Physical activity and all-cause mortality: an updated meta-analysis with different intensity categories. Int J Sports Med. 2009; 30(3):213-224. (Request with CPSBC or view UBC)
- Wen CP, Wai JP, Tsai MK, Yang YC, Cheng TY, Lee MC, et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet. 2011; 378(9798): 1244-1253. (View with CPSBC or UBC)
- Saris WH, Blair SN, van Baak MA, Eaton SB, Davies PS, Di Pietro L, et al. How much physical activity is enough to prevent unhealthy weight gain? Outcome of the IASO 1st Stock Conference and consensus statement. Obes Rev. 2003; 4(2): 101-114. (View with CPSBC or UBC)
- DiPietro L, Kohl HW 3rd, Barlow CE, Blair SN. Improvements in cardiorespiratory fitness attenuate age-related weight gain in healthy men and women: the Aerobics Center Longitudinal Study. Int J Obes Relat Metab Disord. 1998; 22(1): 55-62. (View with CPSBC or UBC)
- McGuire MT, Wing RR, Klem ML, Hill JO. Behavioral strategies of individuals who have maintained long-term weight losses. Obes Res.1999; 7(4): 334-341. (View)
- Malhotra A, Noakes T, Phinney S. It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br J Sports Med. 2015; 49(15): 967-968. (Request with CPSBC or view UBC)
- Hainer V, Toplak H, Stich V. Fit or fat: which is more important? Diabetes Care 2009; 32(suppl)2: S392-S397. (View)
- He XZ, Baker DW. Body mass index, physical activity and the risk of decline in overall health and physical functioning in late middle age. Am J Public Health 2004; 94(9): 1567-1573. (View with CPSBC or UBC)
- Henríquez Sánchez P, Ruano C, de Irala J, Ruiz-Canela M, Martínez-González MA, Sánchez-Villegas A. Adherence to the Mediterranean diet and quality of life in the SUN Project. Eur J Clin Nutr. 2012; 66(3): 360-368. (View with CPSBC or UBC)
- Bize R, Johnson JA, Plotnikoff RC. Physical activity level and health-related quality of life in the general adult population: a systematic review. Prev Med. 2007; 45(6): 401-415. (View with CPSBC or UBC)
- Blissmer B, Riebe D, Dye G, Ruggiero L, Greene G, Caldwell M. Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects. Health Qual Life Outcomes. 2006; 4:43. (View)
- Martin CK, Church TS, Thompson AM, Earnest CP, Blair SN. Exercise dose and quality of life: a randomized controlled trial. Arch Intern Med. 2009; 169(3): 269-278. (Request with CPSBC or view UBC)
- Kraschnewski JL, Boan J, Esposito J, Sherwood NE, Lehman EB, et al. Long-term weight loss maintenance in the United States. Int J Obes (Lond). 2010; 34(11): 1644-1654. (View with CPSBC or UBC)
- Wing RR, Phelan S. Long-term weight loss maintenance. Am J Clin Nutr. 2005; 82(suppl): 222S– 4 225S. (View with CPSBC or UBC)
- MacLean PS, Bergouignan A, Cornier M, Jackman MR. Biology’s response to dieting: the impetus for weight gain. Am J Physiol Regul Integr Comp Physiol. 2011; 301: R581–R600. (View)
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- Winter JE, MacInnis RJ, Wattanapenpaiboon N, Nowson CA. BMI and all-cause mortality in older adults: a meta-analysis. Am J Clin Nutr 2014;99:875–90 (View)
Diabetes and exercise by Dr. Andrew Farquhar http://thischangedmypractice.com/diabetes-and-exercise/