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Low Carbohydrate Diets and Weight Loss David L. Gee, PhD FCSN Nutrition Update Summer 2004

The Low-Carbohydrate Diet of William Banting Age: 66 yrs Weight Loss: –46 pounds of initial 202 pounds –over one year “Never hungry” Letter on Corpulence, Addressed to the Public. 2nd ed., London, England, Harrison and Sons; 1863.

Efficacy and Safety of Low- Carbohydrate Diets: A Systematic Review D. Bravata et al JAMA 2003;289:

Efficacy and Safety of Low-Carbohydrate Diets: A Systematic Review MEDLINE search for low-carbohydrate diet studies from –> 4 days, > 500 Cal/d, reported Cal & CHO content, relevant outcomes 107 articles with 3268 participants –663 participants consuming < 60gCHO/d –71 participants consuming < 20gCHO/d No low-carb diets with participants >53 yo Only 5 studies (non-randomized, no comparison groups) with diet duration of > 90 days.

Efficacy and Safety of Low-Carbohydrate Diets: A Systematic Review Findings: Weight loss in obese subjects associated with: –longer diet duration (p=0.002) –restriction of calorie intake (p=0.03) –but not carbohydrate content (p=0.90) Low-carbohydrate diets had no significant adverse effect on fasting serum lipids, glucose, insulin or blood pressure Concluded: ‘insufficient evidence to make recommendations for or against the use of low- carbohydrate diets…’

A Low-Carbohydrate, Ketogenic Diet Versus a Low-Fat Diet to Treate Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Yancy et al. Annals of Int. Med. 2004; 140: Duke University

A Low-Carbohydrate, Ketogenic Diet Versus a Low- Fat Diet to Treate Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Setting: –Outpatient research clinic Participants: –120 overweight, hyperlipidemic volunteers Intervention: (24 weeks) –Low CHO initially <20g/d, nutritional supplements, exercise recommendation, group meetings –Low Fat < 30% Cal from fat, < 300mg cholesterol, energy deficit of Cal/d, exercise recommendation, group meetings

After 12 weeks: LC diet lost 12 kg, LF diet lost 5.5 kg

Low CHO group had: –greater decreases in TG –increases in HDL-C –greater decreases in TG:HDL ratio but: 2 dropped out due to elevated LDL-C (184 to 3mo., 182 to mo., 30% had elevated LDL-C by >10% compared to 16% on LF diet

A Low-Carbohydrate, Ketogenic Diet Versus a Low- Fat Diet to Treate Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Other findings: Ketonuria –86% positive at 2 weeks –42% positive at 24 weeks Body composition –expected fat mass lost LC = 9.4 kg LF = 4.8 kg % of total weight as fat similar in LC and LF Both groups blood pressure and pulse rate decreased (NS between groups)

A Low-Carbohydrate, Ketogenic Diet Versus a Low- Fat Diet to Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Adverse Effects

A Low-Carbohydrate, Ketogenic Diet Versus a Low- Fat Diet to Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Diet Composition

A Low-Carbohydrate, Ketogenic Diet Versus a Low- Fat Diet to Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial. Conclusions “…a low-carbohydrate diet program had better participant retention and greater weight loss. During active weight loss, serum triglyceride levels decreased more and HDL-C increased more with the LC diet than with the LF diet.”

A Randomized Trial of a Low- Carbohydrate Diet for Obesity G. Foster et al. NEJM 2003;348: U. Penn, U. Colo, Wash U., T. Jefferson U.

A Randomized Trial of a Low-Carbohydrate Diet for Obesity Setting –multi-center outpatient clinics Participants –63 obese subjects, random controlled trial, excluded diabetics Intervention (1 year) –LC Diet RD meeting, 20gCHO/d, gradually increased, Dr. Atkins’ book, ‘self-help’ –LF Diet RD meeting, Cal/d diet, 60% CHO, 25% fat, LEARN Program for Weight Management, ‘self-help’

A Randomized Trial of a Low-Carbohydrate Diet for Obesity Attrition Rate

A Randomized Trial of a Low-Carbohydrate Diet for Obesity Conclusions “LC diet produced greater weight loss … than did the conventional diet for the first six months, but the differences were not significant at one year.” “LC diet was associated with greater improvement in some risk factors for CHD.” “Adherence was poor and attrition high in both groups.”

The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One Year Follow-up of a Randomized Trial L. Stern et al. Ann Intern Med. 2004;140: Phil. VAMC, U. Penn, Drexel U.

The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One Year Follow-up of a Randomized Trial Setting –outpatient clinic Participants –132 adults with BMI >35, 83% with diabetes or metabolic syndrome, RCT Intevention (1 year) –LC diet 30gCHO/day, weekly meeting for 4 weeks, monthly meetings for next 11 months –LF diet reduce Cal by 500 Cal/day, fat < 30%

% Cal from CHO: LC=33%, LF=50% % Cal from FAT: LC=57%, LF=34% SFA & Chol intake not different, Caloric intake in LC tended to be lower

The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One Year Follow-up of a Randomized Trial Summary Weight Loss –LC lost more weight at 6 months than LF –after 6 months, LC maintained weight lost, LF continued to lose weight Serum Lipids –changes in TC and LDL-C were NS between groups –TG decreased more in LF than LC –HDL decreased less in LF than LC

The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One Year Follow-up of a Randomized Trial Summary Glycemic Control –no difference in glycemic control or insulin sensitivity between LC and LF –HbA1c in diabetics was lower in LC than LF Diet –greater weight loss in LC may be due to lower caloric intake –LF was not truly low fat –SFA intake was not different in LF and LC –MUFA intake was higher in LC than LF

The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One Year Follow-up of a Randomized Trial Conclusions: “LC had more favorable overall outcomes at 1 year than did those on LF diets” “Weight loss was similar, but effects on atherogenic dyslipidemia and glycemic control were still more favorable…”

Low-Carb Diets: What have we learned? Weight loss –LC loses more weight at 6 months but differences in weight loss with LF disappear at 12 months –difference in weight loss may be primarily due to caloric intake Attrition –both LC and LF diets have high attrition rates –LF may be more due to lower rate of weight loss and ‘been there, done that’. –LC may be more due to adverse effects and unsatisfactory dietary restrictions.

Low-Carb Diets: What have we learned? Health Risk Factors –TC & LDL-C not different at 1 yr due to weight loss difference, lack of difference in SFA intake –HDL-C higher in LC diets low fat diets tend to lower HDL –TG lower in LC diets less VLDL synthesis in LC –small differences in glycemic control, blood pressure

Low-Carb Diets: What have we learned? Diets –LF diets often not as low in fat as recommended –LC diets often higher in carbs than recommended and may contain less saturated fat than expected. Future