Diet Efficacy in Obesity Gita Majdi
Outline: • Obesity • Diet in obesity management • Types of diet • Comparisons of diets
The optimal management of overweight and obesity requires a combination of diet, exercise, and behavioral modification. • In addition, some patients eventually require pharmacologic therapy or bariatric surgery. Source:Whatis a reasonable weight loss? Patients' expectations and evaluations of obesity treatment outcomes. J Consult Clin Psychol. 1997;65(1):79.
GOALS OF WEIGHT LOSS • An initial weight loss goal of 5 to 7 percent of body weight is realistic for most individuals. • The first goal for any overweight individual is to prevent further weight gain and keep body weight stable (within 5 pounds of its current level). • A weight loss of more than 5 percent can reduce risk factors for cardiovascular disease, such as dyslipidemia, hypertension, and diabetes mellitus . • An average deficit of 500 kcal/day should result in an initial weight loss of approximately 0.5 kg/week (1 lb/week). Source: What is a reasonable weight loss? Patients' expectations and evaluations of obesity treatment outcomes. J Consult Clin Psychol. 1997;65(1):79. Systematic review of long-term weight loss studies in obese adults: clinical significance and applicability to clinical practice. DouketisJD, Macie C, Thabane L, Williamson DF, IntJ Obes (Lond). 2005;29(10):1153.
between 1971 and 2004, the average dietary intake of calories in the United States increased by 22% among women and by 10% among men, primarily owing to the increased consumption of refined carbohydrates, starches, and sugar-sweetened beverages. Source: Lloyd-Jones D, Adams RJ, Brown TM, et al. Heart disease and stroke statistics -- 2010 update: a report from the American Heart Association. Circulation 2010;121:e46-e215[Erratum, Circulation 2010;121(12):e260.]
In the Diabetes Prevention Program, a multi-center trial in patients with impaired glucose tolerance, weight loss of 7 percent reduced the rate of progression from impaired glucose tolerance to diabetes by 58 percent.
Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men DariushMozaffarian, M.D., Dr.P.H., Tao Hao, M.P.H., Eric B. Rimm, Sc.D., Walter C. Willett, M.D., Dr.P.H., and Frank B. Hu, M.D., Ph.D. N Engl J Med 2011; 364:2392-2404June 23, 2011DOI: 10.1056/NEJMoa1014296
Study • Prospective study involving three separate cohorts that included 120,877 U.S. • women and men who were free of chronic diseases and not obese at baseline, with follow-up periods from 1986 to 2006, 1991 to 2003, and 1986 to 2006. • The relationships between changes in lifestyle factors and weight change were evaluated at 4-year intervals, with multivariable adjustments made for age, baseline body-mass index for each period, and all lifestyle factors simultaneously.
Study population • Study participants included 50,422 women in the Nurses' Health Study (NHS), followed for 20 years (1986 to 2006). • 47,898 women in the Nurses' Health Study II (NHS II), followed for 12 years (1991 to 2003). • 22,557 men in the Health Professionals Follow-up Study (HPFS), followed for 20 years (1986 to 2006).
n a multivariable-adjusted analysis, overall dietary changes among the 120,877 men and women in the three cohorts were based on the sum of changes in the intake of fruits, vegetables, whole grains, nuts, refined grains, potatoes or french fries, potato chips, butter, yogurt, sugar-sweetened beverages, 100%-fruit juice, sweets and desserts, processed meats, unprocessed red meats, trans fat, fried foods consumed at home, and fried foods consumed away from home. Panel A shows the relationship between deciles of dietary change and weight change per 4-year period in the three cohorts separately and combined. As compared with persons in the top decile, persons in the bottom decile had a 5.48-lb greater weight gain (95% confidence interval [CI], 4.02 to 6.94). Panel B shows the relationship between the cross-stratified quintiles of changes in both dietary habits and physical activity with weight changes per 4-year period for the combined cohorts. As compared with persons in the top quintiles of both dietary change and physical-activity change.
Conclusion: • Some foods — vegetables, nuts, fruits, and whole grains — were associated with less weight gain when consumption was actually increased. • Their inverse associations with weight gain suggest that the increase in their consumption reduced the intake of other foods to a greater (caloric) extent, decreasing the overall amount of energy consumed. • Yogurt consumption was also associated with less weight gain in all three cohorts.
Rate of Weight Loss • Men lose more weight than women of similar height and weight when they comply with eating any given diet because men have more lean body mass, less percent body fat, and therefore higher energy expenditure. • Older subjects of either sex have a lower energy expenditure and therefore lose weight more slowly than younger subjects; metabolic rate declines by approximately 2 percent per decade (about 100 cal/decade). • Source:Nutrition and aging: changes in the regulation of energy metabolism with aging. Physiol Rev. 2006;86(2):651.
Types of Diets • Conventional diets are defined as those below energy requirements but above 800 kcal/day . • These diets fall into the following groups: • Balanced low-calorie diets/portion-controlled diets (weight watchers) • Low-fat diets (Ornish) • Low-carbohydrate diets (Atkins) • Mediterranean diet Source: Obes Res. 2001 Mar
Balanced low-calorie diets • Eat foods with adequate nutrients in addition to protein, carbohydrate, and essential fatty acids. • Eliminate alcohol, sugar-containing beverages, and most highly concentrated sweets because they rarely contain adequate amounts of other nutrients besides energy
Low-fat diets • In a meta-analysis of trials comparing low-fat diets (typically 20 to 25 percent of energy from fats) with a control group consuming a usual diet or a medium fat diet (usually 35 to 40 percent of energy), there was greater weight loss (approximately 3 kg) with low-fat compared with moderate fat diets. • one report noted that people who successfully keep their weight reduced adopt eating a lower fat diet. • Source: Ann Behav Med. 2009 Oct;38(2):94-104
A low-fat dietary pattern with healthy carbohydrates is not associated with weight gain. • This was illustrated by the Women's Health Initiative Dietary Modification Trial of 48,835 postmenopausal women over age 50 years who were randomly assigned to a 1- dietary intervention that included group and individual sessions to promote a decrease in fat intake and increases in fruit, vegetable, and grain consumption (healthy carbohydrates), but did not include weight loss 2- caloric restriction goals, or a control group which received only dietary educational materials . • After an average of 7.5 years of follow-up, the following results were seen:
Conclusion. • Women in the intervention group lost weight in the first year (mean of 2.2 kg) and maintained lower weight than the control women at 7.5 years (difference of 1.9 kg at one year, and 0.4 kg at 7.5 years). • No tendency toward weight gain was seen in the intervention group overall, or when stratified by age, ethnicity, or body mass index. • Weight loss was related to the level of fat intake and was greatest in women who decreased their percentage of energy from fat the most.
Low-fat dietary pattern and weight change over 7 years: the Women's Health Initiative Dietary Modification Trial. • DESIGN, SETTING, AND PARTICIPANTS: • Randomized intervention trial of 48,835 postmenopausal women in the United States who were of diverse backgrounds and ethnicities and participated in the Women's Health Initiative Dietary Modification Trial; 40% (19,541) were randomized to the intervention and 60% (29,294) to a control group. Study enrollment was between 1993 and 1998, and this analysis includes a mean follow-up of 7.5 years (through August 31, 2004). • INTERVENTIONS: • The intervention included group and individual sessions to promote a decrease in fat intake and increases in vegetable, fruit, and grain consumption and did not include weight loss or caloric restriction goals. The control group received diet-related education materials. • MAIN OUTCOME MEASURE: • Change in body weight from baseline to follow-up. • RESULTS: • Women in the intervention group lost weight in the first year (mean of 2.2 kg, P<.001) and maintained lower weight than control women during an average 7.5 years of follow-up (difference, 1.9 kg, P<.001 at 1 year and 0.4 kg, P = .01 at 7.5 years). No tendency toward weight gain was observed in intervention group women overall or when stratified by age, ethnicity, or body mass index. Weight loss was greatest among women in either group who decreased their percentage of energy from fat. A similar but lesser trend was observed with increases in vegetable and fruit servings, and a nonsignificant trend toward weight loss occurred with increasing intake of fiber. • CONCLUSION: • A low-fat eating pattern does not result in weight gain in postmenopausal women. JAMA. 2006 Jan 4;295(1):39-49
Low carbohydrate • Low (60 to 130 grams of carbohydrates) • very low-carbohydrate diets (0 to <60 grams) • Restriction of carbohydrates leads to glycogen mobilization and, if carbohydrate intake is less than 50 g/day, ketosis will develop. • Rapid weight loss occurs, primarily due to glycogen breakdown and fluid loss rather than fat loss. • Low and very low-carbohydrate diets are more effective for short-term weight loss than low-fat diets, although probably not for long-term weight loss.
High protein diet • Higher protein diets may improve weight maintenance, as illustrated by the results of a study of 60 subjects randomly assigned to a low fat, high protein versus low-fat, high-carbohydrate diet after completing a four week very low calorie diet . • Among the subjects who completed the three-month study (n = 48), the high protein diet group had significantly better weight maintenance (between group difference of 2.3 kg). • Source:Int J Obes (Lond). 2009;33(3):296
Side effects? • High dietary protein intake: • Increases urinary calcium excretion (with potential risk for bone loss and calcium stone formation). • However, two small randomized trials that looked at bone metabolism found evidence that increased dietary protein may decrease bone resorption. • One of the trials found that increased intestinal absorption of calcium was primarily responsible for the increased urinary excretion of calcium and that the excreted calcium was not coming from bone
Effect of dietary protein supplements on calcium excretion in healthy older men and women. • Thirty-two subjects were randomly assigned to daily high (0.75 g/kg) or low (0.04 g/kg) protein supplement groups. • Isocaloric diets were maintained by advising subjects to reduce their intake of carbohydrates. Selected biochemical measurements were made at baseline and on d 35 and either d 49 or 63. • Changes in urinary calcium excretion in the two groups did not differ significantly over the course of the study. The high protein group had significantly higher levels of serum IGF-I (P = 0.008) and lower levels of urinary N-telopeptide (P = 0.038) over the period of d 35-49 or 63. We conclude that increasing protein intake from 0.78 to 1.55 g/kg.d with meat supplements in combination with reducing carbohydrate intake did not alter urine calcium excretion, but was associated with higher circulating levels of IGF-I, a bone growth factor, and lowered levels of urinary N-telopeptide, a marker of bone resorption. • In contrast to the widely held belief that increased protein intake results in calcium wasting, meat supplements, when exchanged isocalorically for carbohydrates, may have a favorable impact on the skeleton in healthy older men and women. • Source:J Clin Endocrinol Metab. 2004;89(3):1169.
The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women. • The study consisted of 2 wk of a well-balanced diet followed by 10 d of an experimental diet containing either moderate (1.0 g/kg) or high (2.1 g/kg) protein. • Thirteen healthy women received both levels of protein in random order. • Intestinal calcium absorption increased during the high-protein diet in comparison with the moderate (26.2 +/- 1.9% vs. 18.5 +/- 1.6%, P<0.0001, mean +/- sem) as did urinary calcium (5.23 +/- 0.37 vs. 3.57 +/- 0.35 mmol/d, P<0.0001, mean +/- sem). • The high-protein diet caused a significant reduction in the fraction of urinary calcium of bone origin and a nonsignificant trend toward a reduction in the rate of bone turnover. • There were no protein-induced effects on net bone balance. • These data directly demonstrate that, at least in the short term, high-protein diets are not detrimental to bone. • Source:J Clin Endocrinol Metab. 2005;90(1):26
Mediterranean diet Include a high level of monounsaturated fat relative to saturated; Moderate consumption of alcohol, mainly as wine; High consumption of vegetables, fruits, legumes, and grains; Moderate consumption of milk and dairy products, mostly in the form of cheese; Relatively low intake of meat and meat products.
Mediterranean diet • This meta-analysis shows, in an overall analysis comprising more than 1.5 million healthy subjects and 40 000 fatal and non-fatal events, that greater adherence to a Mediterranean diet is significantly associated with a reduced risk of overall mortality, cardiovascular mortality, cancer incidence and mortality, and incidence of Parkinson’s disease and Alzheimer’s disease. • Source BMJ. 2008; 337: a1344.:
Very low-calorie diets • Diets with energy levels between 200 and 800 kcal/day are called "very low-calorie diets," while those below 200 kcal/day can be termed starvation diets. • Starvation is the ultimate very low-calorie diet and results in the most rapid weight loss. Starvation diets are now rarely used for treatment of obesity.
Very low-calorie diets have not been shown to be superior to conventional diets for long-term weight loss. • In a meta-analysis of six trials comparing very low-calorie diets with conventional low-calorie diets, short-term weight loss was greater with very low-calorie diets (16.1 versus 9.7 versus percent of initial weight), but there was no difference in long-term weight loss (6.3 versus 5.0 percent). • Source:Obesity. 2006 Aug;14(8):1283-93
Comparison trials • The impact of specific dietary composition on weight change remains uncertain. • When energy from dietary carbohydrates decreases, energy from fat sources tends to increase. • When energy from dietary fats decreases, energy from carbohydrate sources tends to increase. • The debate has mainly centered on whether low-fat or low-carbohydrate diets can better induce weight loss and sustain it over the long-term. • Some of these initial comparison trials of different dietary regimens had important limitations . These included high dropout rates (21 to 48 percent), suboptimal dietary compliance, and limited long-term follow-up.
Weight loss diets • Initial trials evaluating the effect of type of diet (predominantly low-carbohydrate versus low-fat) on weight loss and other outcomes showed that weight loss at six months was approximately 4 kg greater in the very low-carbohydrate group than in the low-fat group. • Trials lasting for one year, however, did not find a significant difference in weight loss.
OBJECTIVE: To compare the effects of a low-carbohydrate, ketogenic diet program with those of a low-fat, low-cholesterol, reduced-calorie diet • 120 overweight, hyperlipidemic volunteers from the community. • Low-carbohydrate diet (initially, <20 g of carbohydrate daily) plus nutritional supplementation, exercise recommendation, and group meetings • low-fat diet (<30% energy from fat, <300 mg of cholesterol daily, and deficit of 500 to 1000 kcal/d) plus exercise recommendation and group meetings. • CONCLUSIONS: • Compared with a low-fat diet, a low-carbohydrate diet program had better participant retention and greater weight loss. During active weight loss, serum triglyceride levels decreased more and high-density lipoprotein cholesterol level increased more with the low-carbohydrate diet than with the low-fat diet. • Source:Ann Intern Med. 2004 May 18;140(10):769-7
Longer Follow up • Meta-analyses of trials comparing low-fat and low-carbohydrate diets found that the difference in weight loss at six months (weighted mean difference 3 to 4 kg), favoring the low carbohydrate over low fat diet, was not sustained at 12 to 24 months (weighted mean difference 1 kg) • In one study, this convergence was mainly due to regain of weight in the low-carbohydrate group . • In another, the convergence was due to ongoing weight loss in the low-fat group. • Source:Ann Intern Med. 2004;140(10):778
Comparison of mean weight loss in kg between subjects on a conventional diet (red circles) and a low-carbohydrate diet (blue squares). The difference in weight loss was no longer significant at one year. Data from: Stern L, Iqbal N, Seshadri P, et al. The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial. Ann Intern Med 2004; 140:778.
Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet Iris Shai, R.D., Ph.D., Dan Schwarzfuchs, M.D., Yaakov Henkin, M.D., Danit R. Shahar, R.D., Ph.D., Shula Witkow, R.D., M.P.H., Ilana Greenberg, R.D., M.P.H., Rachel Golan, R.D., M.P.H., Drora Fraser, Ph.D., ArkadyBolotin, Ph.D., HilelVardi, M.Sc., OsnatTangi-Rozental, B.A., Rachel Zuk-Ramot, R.N., Benjamin Sarusi, M.Sc., DovBrickner, M.D., Ziva Schwartz, M.D., EinatSheiner, M.D., Rachel Marko, M.Sc., Esther Katorza, M.Sc., Joachim Thiery, M.D., Georg Martin Fiedler, M.D., Matthias Blüher, M.D., Michael Stumvoll, M.D., and Meir J. Stampfer, M.D., Dr.P.H. for the Dietary Intervention Randomized Controlled Trial (DIRECT) Group N Engl J Med 2008; 359:229-241July 17, 2008
322 moderately obese subjects (86 percent men) were randomly assigned to a low-fat (restricted calorie), Mediterranean (moderate-fat, restricted calorie, rich in vegetables, low in red meat), or low-carbohydrate (non-restricted-calorie) diet for two years. Adherence rates were higher than those reported in previous trials (95.4 and 84.6 percent at one and two years, respectively). Weight loss was greater with the Mediterranean and low-carbohydrate diets than the low-fat diet (mean weight loss 4.4, 4.7, and 2.9 kg, respectively). The most favorable effect on lipids (increased high-density lipoprotein [HDL] and decreased triglycerides and ratio of total cholesterol to HDL) was seen in the low-carbohydrate group. Among subjects with type 2 diabetes, the greatest improvement in glycemic control occurred with the Mediterranean diet. Among all groups, weight loss was greater for those who completed the two year study than for those who withdrew.
Vertical bars indicate standard errors. To statistically evaluate the changes in weight measurements over time, generalized estimating equations were used, with the low-fat group as the reference group. The explanatory variables were age, sex, time point, and diet group.
Panel A shows the results for serum high-density lipoprotein (HDL) cholesterol, Panel B for serum triglycerides, Panel C for serum low-density lipoprotein (LDL) cholesterol, and Panel D for the ratio of total cholesterol to HDL cholesterol. Vertical bars indicate standard deviations. To statistically evaluate the changes in weight measurements over time, generalized estimating equations were used, with the low-fat group as the reference group. The explanatory variables were age, sex, time point, and diet group. Results are presented for the 82% of the study population (263 participants) with blood-sample data at all time points (90 in the low-fat group, 92 in the Mediterranean-diet group, and 81 in the low-carbohydrate group). The P values for the comparison between the low-fat group and the Mediterranean-diet group are 0.94 for HDL cholesterol, 0.21 for triglycerides, 0.41 for LDL cholesterol, and 0.23 for the ratio of total cholesterol to HDL cholesterol. The P values for the comparison between the low-fat group and the low-carbohydrate group are 0.01 for HDL cholesterol, 0.03 for triglycerides, 0.94 for LDL cholesterol, and 0.01 for the ratio of total cholesterol to HDL cholesterol. To convert values for
In this 2-year dietary-intervention study: • Mediterranean and low-carbohydrate diets are effective alternatives to the low-fat diet for weight loss and appear to be just as safe as the low-fat diet. • The similar caloric deficit achieved in all diet groups suggests that a low-carbohydrate, non–restricted-calorie diet may be optimal for those who will not follow a restricted-calorie dietary regimen. • The increasing improvement in levels of some biomarkers over time up to the 24-month point, despite the achievement of maximum weight loss by 6 months, suggests that a diet with a healthful composition has benefits beyond weight reduction.
Results: • Two phases of weight change: • initial weight loss and weight maintenance. • The maximum weight reduction was achieved during the first 6 months. • this period was followed by the maintenance phase of partial rebound and a plateau. • Among all diet groups, weight loss was greater for those who completed the 24-month study than for those who did not. • Even moderate weight loss has health benefits • Behavioral approaches yield weight losses similar to those obtained with pharmacotherapy.
They observed two phases of weight change: initial weight loss and weight maintenance. • The maximum weight reduction was achieved during the first 6 months; this period was followed by the maintenance phase of partial rebound and a plateau. • Among all diet groups, weight loss was greater for those who completed the 24-month study than for those who did not. Even moderate weight loss has health benefits, and our findings suggest benefits of behavioral approaches that yield weight losses similar to those obtained with pharmacotherapy.
Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates Frank M. Sacks, M.D., George A. Bray, M.D., Vincent J. Carey, Ph.D., Steven R. Smith, M.D., Donna H. Ryan, M.D., Stephen D. Anton, Ph.D., Katherine McManus, M.S., R.D., Catherine M. Champagne, Ph.D., Louise M. Bishop, M.S., R.D., Nancy Laranjo, B.A., Meryl S. Leboff, M.D., Jennifer C. Rood, Ph.D., Lilian de Jonge, Ph.D., Frank L. Greenway, M.D., Catherine M. Loria, Ph.D., Eva Obarzanek, Ph.D., and Donald A. Williamson, Ph.D. N Engl J Med 2009; 360:859-873February 26, 2009DOI: 10.1056/NEJMoa0804748
Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women • The A TO Z Weight Loss Study: A Randomized Trial • Christopher D. Gardner, PhD; Alexandre Kiazand, MD; SofiyaAlhassan, PhD; Soowon Kim, PhD; Randall S. Stafford, MD, PhD; Raymond R. Balise, PhD; Helena C. Kraemer, PhD; Abby C. King, PhD • Stanford Prevention Research Center and the Department of Medicine, Stanford University Medical School, Stanford, Calif. • Source: Jama 2007
Atkins (very low in carbohydrate ) • Zone (low in carbohydrate), • LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition; low in fat, high in carbohydrate, based on national guidelines) • Ornish (very high in carbohydrate).