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“You should try to lose some weight”: an evidence-‐based approach to diet and weight loss Ridge Meadows Hospital Grand Rounds 14 September 2015 Barbara Hughes, MD, FRCPC
DefiniMons Body Mass Index=weight in kilograms/ (height in metres)2
Normal=18.5-‐24.9
Overweight=25-‐29.9
Obese=30+
The problem Increases all cause mortality
Heart disease, stroke, hypertension, hyperlipidemia, diabetes
Sleep apnea, asthma
Gallbladder disease, gallbladder cancer, colon cancer, breast cancer Endometrial cancer
Kidney cancer OsteoarthriMs, gout Pain, mental illness
The problem Stats Canada 2011: 33% overweight 18% obese In BC: 30% overweight 14% obese In 2010, Canada was 3rd faaest country in the G7 (behind US and Germany)
The problem How to reduce body weight? How to maintain a lower body weight?
How to prevent further weight gain? Approaches include diet therapy, physical acMvity, behaviour therapy, pharmacotherapy, surgery, and combinaMons
Focus on diet therapy and physical acMvity
Sources NaMonal InsMtutes of Health Clinical Guidelines on the IdenMficaMon, EvaluaMon, and Treatment of Overweight and Obesity in Adults: The Evidence Report 1998
Update 2013
Canadian clinical pracMce guidelines on the management and prevenMon of obesity in adults and children 2006
Literature review
Diet therapy
Diet therapy NIH review of 34 randomized controlled trials of low calorie diets (LCDs), consisMng of 1000-‐1200 kcal/day
25 of the trials lasted ≥6 months, 9 lasted 12-‐21 weeks
All studies showed that LCDs resulted in weight loss Studies with a duraMon of ≥6 months led to a mean weight loss of about 8% of body weight over a period of 6-‐12 months
Studies with a duraMon of 3-‐6 months also led to a weight loss of about 8%
4 studies that included a long-‐term weight loss and weight maintenance intervenMon lasMng 3-‐4½ years led to an average weight loss of 4%
Diet therapy NIH reviewed 4 randomized controlled trials of very low calorie diets (VLCDs), consisMng of about 400-‐500 kcal/day, compared to LCDs
VLCDs for 12-‐16 weeks, then LCD for total duraMon of 24 weeks to 5 years Trials involved mainly extremely obese women
VLCDs led to weight loss of about 13-‐23 kg, compared to 9-‐13 kg with LCDs at the end of the acMve phase
Over the medium term of 6-‐12 months, VLCDs resulted in 1.1-‐10.4 kg greater weight loss than LCDs
Aler 1 year, no advantage of VLCDs over LCDs
Diet therapy Which diet?
Low fat vs low carb?
Diet therapy Dansinger et al. Comparison of the Atkins (low carb, 20-‐50g/day), Ornish (10% fat), Weight Watchers (calorie restricted), and Zone Diets (40% carb, 30% protein, 30% fat) for Weight Loss and Heart Disease Risk ReducMon. JAMA 2005; 293(1):43-‐53
160 subjects, average BMI 35, aged 22-‐72, with known hypertension, hyperlipidemia, or fasMng hyperglycemia, randomized to the above diets, followed for 1 year, changes in body weight and cardiac risk factors
Mean weight loss at 1 year was 2.1 kg for Atkins, 3.2 kg for Zone, 3.0 kg for Weight Watchers, 3.3kg for Ornish
Each reduced LDL to HDL raMo by 10%, no significant effects on blood pressure or blood glucose
Diet therapy Gardner et al. Comparison of the Atkins (20-‐50g/day carbohydrate), Zone (40% carb-‐30% protein-‐30% fat), Ornish (10% fat), and LEARN (55-‐60% carbohydrate, 10% saturated fat) diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women, The A to Z Weight Loss Study: A Randomized Trial. JAMA 2007;297(9):969-‐977.
311 women, BMI 27-‐40, 12 months, randomized to 1 of 4 diets At 12 months, mean weight loss 4.7 kg for Atkins, 1.6 kg Zone, 2.6 kg LEARN, 2.2 kg Ornish
Significantly more weight loss for Atkins at 6 months
Atkins diet had more favourable effects on metabolic profile
Diet therapy Stern et al. The Effects of Low-‐Carbohydrate versus ConvenMonal Weight Loss Diets in Severely Obese Adults: One-‐Year Follow-‐up of a Randomized Trial. Ann Intern Med. 2004; 140: 778-‐785
132 adults, BMI ≥35, 83% had diabetes or metabolic syndrome
Randomized to low carbohydrate diet, <30 g/day, or convenMonal diet, 500 fewer calories per day with <30% from fat
By 1 year, mean weight change with low carb diet was 5.1 kg vs 3.1 kg with low fat diet p=0.2
Low carb diet had more favourable effects on triglycerides and less decrease in HDL, lower Hgb A1C
Diet therapy Shai et al. Weight loss with a Low-‐Carbohydrate, Mediterranean, or Low-‐Fat diet. NEJM 2008; 359: 229-‐41.
2 year trial, 322 subjects, mean age 52, mean BMI 31, 86% male
Randomized to one of three diets: low-‐fat, restricted-‐calorie; Mediterranean, restricted-‐calorie; or low carbohydrate, non-‐restricted-‐calorie
Mean weight loss was 2.9 kg for low fat diet, 4.4 kg for Mediterranean diet, and 4.7 kg for low carbohydrate diet
ReducMon of raMo of total cholesterol to HDL was 20% in low carbohydrate group and 12% in low fat group
For subjects with diabetes, changes in fasMng glucose and insulin levels were more favourable among those on the Mediterranean diet than the low fat diet
Diet therapy Sacks et al. Comparison of Weight-‐Loss Diets with Different ComposiMons of Fat, Protein, and Carbohydrates. NEJM 2009;360:859-‐73.
811 adults randomly assigned to 1 of 4 diets followed for 2 years
Fat, protein, carbohydrates—20-‐15-‐65% (low fat, average protein), 20-‐25-‐55% (low fat, high protein), 40-‐15-‐45% (high fat, average protein), 40-‐25-‐35% (high fat, high protein)
Aler 6 months, average weight loss 6 kg
Began to regain weight aler 12 months
By 2 years, weight loss was similar, about 3 kg
Diets all improved lipid-‐related risk factors and fasMng insulin levels
Diet therapy Nordmann et al. Effects of Low-‐Carbohydrate vs Low-‐Fat diets on Weight Loss and Cardiovascular Risk Factors: A Meta-‐analysis of Randomized Controlled Trials. Arch Intern Med. 2006, 166(3):285-‐293.
Trials comparing effects of low carbohydrate diets without calorie restricMon vs low-‐fat diets in subjects with BMI at least 25, at least 6 month follow up
5 trials, 447 subjects Aler 6 months, low carb lost 3.5 kg more than low fat; aler 12 months, no difference
Triglycerides and HDL beaer in low carb, but total cholesterol and LDL beaer in low fat
Diet therapy Boaom line:
Low carb diet may be more effecMve in the short term
In the longer term, no difference among diets
Choose a diet that fits in with preferences and lifestyle to make adherence easier
Physical acMvity NIH reviewed 13 randomized controlled trials of the effect of physical acMvity on weight loss, abdominal fat, and changes in cardiorespiratory fitness
Most of the studies looked at cardiovascular endurance acMviMes ex. Aerobic dance, brisk walking, jogging, running, staMonary cycling
Intensity 60-‐85% of individual’s esMmated maximum heart rate or 70% of VO₂ max
3-‐7 sessions per week for 30-‐60 minutes
Studies lasted 16 weeks-‐1 year
Physical acMvity 12 Randomized controlled trials studied the effect of physical acMvity, mainly aerobic exercise, on weight loss compared to controls
In 10 of the trials, the exercise group lost a mean of 2.4 kg (2.4% reducMon in body weight, 2.7% reducMon in BMI) compared to the control group
In 2 trials, there was no benefit of physical acMvity on weight loss and showed weight gain in the exercise group compared to the control group
10 randomized controlled trials had a diet-‐only group compared to an exercise-‐only group, diet group led to about 3% or 3 kg greater weight loss than the exercise group
A meta-‐analysis of 28 studies on the effect of exercise on weight loss compared to diet or control groups showed that aerobic exercise alone leads to weight loss of 3 kg in men and 1.4 kg in women, compared to controls (Eur J Clin Nutr 1995 49, 1-‐10)
Physical acMvity Boaom line:
Results in modest weight loss
Can help sustain weight loss over Mme
Can help prevent weight gain, maintains lean body mass and metabolic rate
Independent reducMon in cardiovascular risk
Increases cardiovascular fitness
Diet plus physical acMvity Strong evidence that the combinaMon of diet and physical acMvity produces greater weight loss than either alone
NIH review 15 randomized controlled trials
Each compared combinaMon intervenMon to diet alone, and 6 also compared combinaMon intervenMon to physical acMvity alone
Physical acMvity usually 30-‐60 minutes 3 Mmes a week, 60-‐80% maximum heart rate
Diet components: general dietary advice, 500-‐1000 kcal/day reducMon, or 1200 kcal/day diet
Diet plus physical acMvity 12/15 studies found that combined group had a mean greater weight loss of 1.9 kg and a mean greater BMI reducMon of 0.4 than the diet-‐alone group
5/6 studies that compared combined intervenMon with physical acMvity alone found that combined group had a mean 5.3 kg greater weight loss and 0.9 change in BMI than the physical acMvity-‐alone group
Also found that combinaMon led to 1.5-‐3 kg greater weight loss than diet alone over the longer term of 9 months to 2 years
Diet plus physical acMvity Miller et al. A meta-‐analysis of the past 25 years of weight loss research using diet, exercise or diet plus exercise intervenMon. Interna5onal Journal of Obesity 1997 21, 941-‐947.
493 studies, subjects about 40 y o, BMI about 33, for about 15 weeks
Weight lost through diet 10.7 kg, exercise 2.9 kg, and diet plus exercise 11.0 kg
At one year follow up, diet plus exercise tended to be best, with a maintained weight loss of about 8.6 kg
Weight maintenance Difficult to maintain weight loss over 3-‐5 years
Randomized controlled trials suggest that weight lost will be regained unless a weight maintenance program of diet, exercise, and behavior therapy is conMnued indefinitely
Weight maintenance should be a priority aler the iniMal 6 months of weight loss therapy
Adults in Western countries gain about 0.5-‐1 kg/year
Weight maintenance should be a goal for all of us!
Why do we gain weight? ?OveresMmaMon of calories burned by exercise
?UnderesMmaMon of calorie content of food
?Decline of metabolism with aging
?Differences in efficiency of digesMon
?Difference in gut microbiome
?High simple carbohydrate diet leads to insulin excess
?Obesogenic environment
?Psychological factors ?GeneMc factors
One thing about behavior therapy Burke et al. Self-‐monitoring in Weight Loss: A SystemaMc Review of the Literature. J Am Diet Assoc. 2011; 111(1):92-‐102.
“Self-‐monitoring is the centerpiece of behavioral weight loss intervenMon programs.”
22 studies (1993-‐2009) reporMng on relaMonship between weight loss and the self-‐monitoring strategies of recording dietary intake and exercise, and self-‐weighing
Despite weakness of the evidence due to methodological limitaMon, a significant associaMon between self-‐monitoring and weight loss was consistently found
PrevenMon of overweight and obesity Needs to start in childhood! EPODE study, Romon et al. Public Health Nutr 2009 12(10)1735-‐42.
Ensemble Prevenons l’Obesite des Enfants
Fleurbaix LavenMe Ville Sante study Prevalence of obesity and overweight 1992 FLVS 11.4%, comparison villages 12.6% (p=0.6), 2004 FLVS 8.8%, comparison villages 17.8% (p=<0.0001)
IntervenMon at community level: schools, pre-‐schools, school catering, sports and parents’ associaMons, health professionals, local government, stakeholders from the public and private sectors
Expanding into a world wide network
My take home messages
Stay acMve: at least 30 minutes a day of acMvity, both aerobic endurance and resistance exercises
Eat as few processed foods as possible: avoid trans fats, avoid simple carbohydrates, eat more fruits and vegetables, eat more fibre
PorMon control
Self-‐monitor: weigh yourself regularly, keep a food and exercise diary if acMvely trying to lose weight
