In Brief The obesity paradox (survival advantage in overweight/obese patients with DISEASE HEART TO PREVENT DIABETES AND CORONARY FROM RESEARCH TO PRACTICE/FOUR OPPORTUNITIES type 2 diabetes) has called into question the importance of weight loss in over- weight people with diabetes. A systematic review of weight loss studies with a minimum of 1-year outcomes in people with diabetes reported inconsistent beneficial effects of weight loss on A1C, lipids, and blood pressure. To lower the risk of cardiovascular disease, a better nutrition therapy intervention may be reducing energy intake, which may or may not lead to weight loss, and selecting cardioprotective foods in appropriate portion sizes. However, any nutrition therapy intervention must be based on lifestyle changes the person with diabetes is willing and able to make. The Obesity Paradox and Diabetes It is being called the “obesity para- to heavier patients, cardioprotective dox”: research findings that people metabolic effects of increased body Marion J. Franz, MS, RD, CDE with obesity-related illnesses and who fat, and/or beneficial effects of higher are overweight or obese have better metabolic reserves.1 outcomes, including less mortality, A U-shaped association of weight than their normal-weight peers.1 These with mortality is reported in people seemingly contradictory results have with diabetes. In a recent study,4 the also been shown to apply to people records of 106,640 people with type with acute coronary syndrome, stroke, 2 diabetes in Scotland were reviewed and diabetes.2–9 The consequences of and BMI recorded around the time obesity are clear: increased risk for of diagnosis and mortality through- diabetes, high blood pressure, heart out the next ~ 5 years was assessed. disease, stroke, and kidney disease.10 Mortality risk was higher in people So, the question of emerging interest with a BMI of 20 to < 25 kg/m2 and becomes why, then, once the disease in those with a BMI ≥ 35 kg/m2. develops, does being overweight Vascular mortality was also higher appear to be beneficial? for each 5-kg/m2 increase in BMI > Flegal et al.,1 in a systematic review 30 kg/m2 but was lower below this and meta-analysis, reported that, in level. Another study5 assessed the the general public, severe obesity was relationships between BMI and all- associated with an increased risk for cause mortality in African-American death from all causes but that lesser and white men with type 2 diabetes amounts of excess weight either did and observed a significantly higher not increase this risk or were pro- mortality risk (70%) in those with tective. They concluded, “. excess a BMI within the normal range mortality in obesity may predomi- (18.5–24.9 kg/m2) than in heavier nantly be due to elevated mortality at subjects, with a higher mortality rate higher body mass index (BMI) levels. in African Americans (95%) than in Overweight was associated with sig- whites (53%). In a study of patients nificantly lower all-cause mortality.” who developed diabetes,6 total, car- They further noted that these results diovascular, and noncardiovascular are consistent with previous findings mortality rates were higher among that have also shown lower mortal- normal-weight than among obese ity among overweight and moderately subjects. This finding was true regard- obese patients. Possible explanations less of diabetes type. Two other include earlier medical care and recent studies, Translating Research aggressive risk factor treatment given into Action for Diabetes7 and the Diabetes Spectrum Volume 26, Number 3, 2013 145 PROactive trial,8 also observed that Weight Loss and Diabetes-Related kg.24 In the trials reporting data col- participants who were of normal Outcomes lected for > 1 year, none of the average weight at the baseline examination A PubMed search was conducted to weight losses were back to baseline by or who lost weight during the trial determine the outcomes from base- the end of the studies. (PROactive) experienced higher mor- line to study completion of nutrition tality than participants who were therapy weight loss interventions in A1C results All of the studies reported the effect overweight or obese. This obesity overweight or obese adults with type 2 of weight loss on 1-year A1C values. paradox (survival advantage in obese diabetes. Research was reviewed from Improvements in A1C were reported patients with type 2 diabetes) was 1 January 2000 to 1 February 2013. Eleven randomized, clinical trials from eight of the weight loss inter- also shown to exist in patients with ventions.15,18,21,22,25 However, one of 9 with a completion rate of ≥ 70% and diabetes and cancer. Similar findings 18 12-month laboratory data reported the trials extending to 18 months had been reported in two earlier stud- reported significant improvements 11,12 were identified and are included in ies. All of the above brings into Table 1.15–27 Because the duration of in A1C at 12 months that were not question the role of weight manage- trials affects their outcomes, and to maintained to 18 months. The MED ment in people with chronic diseases, better compare outcomes among stud- reported the largest improvement in especially in people with diabetes. ies, 1-year outcomes are presented in A1C at 1 year, –1.2%,21 and the ILI the table for all trials. However, also reported the second largest, –0.64%.25 Weight Loss/Management: included are data from two trials Significant improvements in A1C were Prevention Versus Treatment reporting 18-month data,18,19 two with also reported from the use of meal of Diabetes 2-year data,23,24 and two with 4-year replacements15 and one low-fat,21 one The research results described above data.21,25–27 One trial21 did not report high-protein,22 and one high-CHO22 suggest that, perhaps, guidelines rec- the statistical significance of interven- study. At 4 years, the MED and ILI ommending weight loss should apply tion changes from baseline to study reported continued improvements primarily to prevention and not neces- end, and one trial25 reported statistical in A1C, –0.9 and –0.36%, respec- sarily to treatment of chronic diseases, significance for the intervention arm tively.21,27 Perhaps of equal importance including diabetes. Strong evidence only; however, both trials are included is that nonsignificant changes in A1C exists for the benefits of moderate in the intervention summaries. were reported from 11 weight loss 16,17,19,20,23,24 weight loss for the prevention of type Eight of the studies compared interventions at 1 year and 18 2 diabetes.13 The question becomes, varying weight loss interventions (10 from one study at 18 months. what are the benefits from weight loss different interventions),17–24 and three Also of interest, five trials com- pared weight loss interventions with as glycemic impairments progress from studies compared the intervention to 15,16,25,27 differing macronutrient percentages prediabetes to overt type 2 diabetes? usual care or to a control group. (high-MUFA vs. high-CHO,19 low- The goals of medical nutrition Weight loss interventions imple- mented in 19 study arms included CHO vs. low-fat,20 high-protein therapy (MNT) for individuals with 22,23 meal replacements (2 studies),15,17 indi- vs. high-CHO, and low-CHO diabetes include achieving and main- 24 vidualized food plans (2 studies),16,17 vs. low-fat ). All five reported that taining blood glucose levels in the one study with two group behavioral weight changes did not differ sta- normal range or as close to normal weight management arms,18 low fat tistically between arms, and weight as is safely possible, a lipid and lipo- (3 studies), 20,21,24 high monounsatu- losses ranged from 1.9 to 4.0 kg. protein profile that reduces the risk rated fat (MUFA),19 high carbohydrate Furthermore, eight of the interven- for cardiovascular disease (CVD), and (CHO) (3 studies),19,22,23 low CHO tion arms reported nonsignificant blood pressure levels in the normal (2 studies), 20,24 high protein (2 stud- changes in A1C from baseline to study range or as close to normal as is safely ies), 22,23 Mediterranean-style diet end,19,20,23,24 and only two intervention possible.13 To achieve these goals, (MED),21 and intensive lifestyle inter- arms (in one study) reported signifi- weight loss has been recommended vention (ILI).25–27 Although physical cant but modest changes in A1C.22 for all overweight or obese individu- activity was suggested or encouraged These findings support a conclusion als who have diabetes or are at risk in several studies,16,18,19,20,22 only two that a variety of eating patterns with for diabetes, with the level of evidence studies, those testing MED and ILI, differing macronutrient percentages rated A (clear evidence from well-con- included physical activity recommen- are moderately effective for weight loss ducted, generalizable, randomized, dations and measured and reported but may not improve A1C levels. 21,25,27 15,17,23,24 controlled trials that are adequately adherence. Four studies Weight loss interventions reporting improvements in A1C at 1 year had powered).14 But perhaps the benefits did not mention physical activity. weight losses of 4.8, 4.2, 3.0, 2.7, 2.2, of weight loss in the treatment of type Weight changes and 1.0 kg, with the MED (–6.2 kg, 2 diabetes need to be reexamined. An Weight losses from interventions 7.2%) and ILI (8.4 kg, 8.6%) hav- inconclusive picture emerges from ranged from 1.9 to 8.4 kg at 12 ing larger weight losses. Weight loss review of the benefits of weight loss months; 16 of the interventions15–24 interventions reporting no statistically on A1C, lipids, and blood pressure reported weight losses ranging from significant improvement in A1C at 1 in people with type 2 diabetes.