***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Epidemiologic data and animal experiments suggest that dietary fat may influence risk of  breast cancer .  To determine whether intervention with a low-fat , high-carbohydrate diet would reduce breast cancer incidence in women at increased risk of the disease , we carried out a r and omized controlled trial in Canada . We recruited 4,690 women with extensive mammographic density and r and omized them to an intervention group or a comparison group . The intervention group received intensive dietary counseling to reduce fat intake to a target of 15 % of calories and increase carbohydrate to 65 % of calories . Dietary intakes were assessed throughout using food records . Subjects were followed for at least 7 years and for an average of 10 years . The main outcome was invasive breast cancer . Percentage of calories from fat in the intervention group decreased from 30 % at baseline to 20 % after r and omization and remained 9 % to 10 % lower than the comparison group throughout . There were 118 invasive breast cancers in the intervention group and 102 in the comparison group [ adjusted hazard ratio = 1.19 ( 95 % CI : 0.91 - 1.55 ) ] . Analysis of food records showed that fat intake at baseline and after r and omization was not associated with total breast cancer incidence . Greater weight and lower carbohydrate intake at baseline and after r and omization were associated with an increased risk of estrogen receptor (ER)-positive breast cancer . Our findings suggest that a sustained reduction in dietary fat intake did not reduce risk of breast cancer  in women with extensive mammographic density .  Weight and carbohydrate intakes were associated with risk of ER-positive breast cancer CONTEXT Popular diets , particularly those low in carbohydrates , have challenged current recommendations advising a low-fat , high-carbohydrate diet for weight loss . Potential benefits and risks have not been tested adequately . OBJECTIVE To compare 4 weight-loss diets representing a spectrum of low to high carbohydrate intake for effects on weight loss and related metabolic variables . DESIGN , SETTING , AND PARTICIPANTS Twelve-month r and omized trial conducted in the United States from February 2003 to October 2005 among 311 free-living , overweight/obese ( body mass index , 27 - 40 ) nondiabetic , premenopausal women . INTERVENTION Participants were r and omly assigned to follow the Atkins ( n = 77 ) , Zone ( n = 79 ) , LEARN ( n = 79 ) , or Ornish ( n = 76 ) diets and received weekly instruction for 2 months , then an additional 10-month follow-up . MAIN OUTCOME MEASURES Weight loss at 12 months was the primary outcome . Secondary outcomes included lipid profile ( low-density lipoprotein , high-density lipoprotein , and non-high-density lipoprotein cholesterol , and triglyceride levels ) , percentage of body fat , waist-hip ratio , fasting insulin and glucose levels , and blood pressure . Outcomes were assessed at months 0 , 2 , 6 , and 12 . The Tukey studentized range test was used to adjust for multiple testing . RESULTS Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months , and mean 12-month weight loss was significantly different between the Atkins and Zone diets ( P<.05 ) . Mean 12-month weight loss was as follows : Atkins , -4.7 kg ( 95 % confidence interval [ CI ] , -6.3 to -3.1 kg ) , Zone , -1.6 kg ( 95 % CI , -2.8 to -0.4 kg ) , LEARN , -2.6 kg ( -3.8 to -1.3 kg ) , and Ornish , -2.2 kg ( -3.6 to -0.8 kg ) . Weight loss was not statistically different among the Zone , LEARN , and Ornish groups . At 12 months , secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups . CONCLUSIONS In this study , premenopausal overweight and obese women assigned to follow the Atkins diet , which had the lowest carbohydrate intake , lost more weight at 12 months than women assigned to follow the Zone diet , and had experienced comparable or more favorable metabolic effects than those assigned to the Zone , Ornish , or LEARN diets [ corrected ] While questions remain about long-term effects and mechanisms , a low-carbohydrate , high-protein , high-fat diet may be considered a feasible alternative recommendation for weight loss . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00079573 Aims /hypothesisThe study aim ed to compare the effects of a 2 year intervention with a low-fat diet ( LFD ) or a low-carbohydrate diet ( LCD ) , based on four group meetings to achieve compliance . Methods This was a prospect i ve r and omised parallel trial involving 61 adults with type 2 diabetes consecutively recruited in primary care and r and omised by drawing ballots . Patients that did not speak Swedish could not be recruited . The primary outcomes in this non-blinded study were weight and HbA1c . Patients on the LFD aim ed for 55–60 energy per cent ( E% ) and those on LCD for 20 E% from carbohydrate . Results The mean BMI and HbA1c of the participants were 32.7 ± 5.4 kg/m2 and 57.0 ± 9.2 mmol/mol , respectively . No patients were lost to follow-up . Weight loss did not differ between groups and was maximal at 6 months : LFD −3.99 ± 4.1 kg ( n = 31 ) ; LCD −4.31 ± 3.6 kg ( n = 30 ) ; p < 0.001 within groups . At 24 months , patients on the LFD had lost −2.97 ± 4.9 kg and those on LCD −2.34 ± 5.1 kg compared with baseline ( p = 0.002 and p = 0.020 within groups , respectively ) . HbA1c fell in the LCD group only ( LCD at 6 months −4.8 ± 8.3 mmol/mol , p = 0.004 , at 12 months −2.2 ± 7.7 mmol/mol , p = 0.12 ; LFD at 6 months −0.9 ± 8.8 mmol/mol , p = 0.56 ) . At 6 months , HDL-cholesterol had increased with the LCD ( from 1.13 ± 0.33 mmol/l to 1.25 ± 0.47 mmol/l , p = 0.018 ) while LDL-cholesterol did not differ between groups . Insulin doses were reduced in the LCD group ( 0 months , LCD 42 ± 65 E , LFD 39 ± 51 E ; 6 months , LCD 30 ± 47 E , LFD 38 ± 48 E ; p = 0.046 for between-group change ) . Conclusions /interpretationWeight changes did not differ between the diet groups , while insulin doses were reduced significantly more with the LCD at 6 months , when compliance was good . Thus , aim ing for 20 % of energy intake from carbohydrates is safe with respect to cardiovascular risk compared with the traditional LFD and this approach could constitute a treatment alternative . Trial registration : Clinical Trials.gov NCT01005498 Funding : University Hospital of Linköping Research Funds , Linköping University , the County Council of Östergötl and , and the Diabetes Research Centre of Linköping BACKGROUND The appropriate dietary intervention for overweight persons with type 2 diabetes mellitus ( DM2 ) is unclear . Trials comparing the effectiveness of diets are frequently limited by short follow-up times and high dropout rates . AIM The effects of a low carbohydrate Mediterranean ( LCM ) , a traditional Mediterranean ( TM ) , and the 2003 American Diabetic Association ( ADA ) diet were compared , on health parameters during a 12-month period . METHODS In this 12-month trial , 259 overweight diabetic patients ( mean age 55 years , mean body mass index 31.4 kg/m(2 ) ) were r and omly assigned to one of the three diets . The primary end-points were reduction of fasting plasma glucose , HbA1c and triglyceride ( TG ) levels . RESULTS 194 patients out of 259 ( 74.9 % ) completed follow-up . After 12 months , the mean weight loss for all patients was 8.3 kg : 7.7 kg for ADA , 7.4 kg for TM and 10.1 kg for LCM diets . The reduction in HbA1c was significantly greater in the LCM diet than in the ADA diet ( -2.0 and -1.6 % , respectively , p < 0.022 ) . HDL cholesterol increased ( 0.1 mmol/l + /- 0.02 ) only on the LCM ( p < 0.002 ) . The reduction in serum TG was greater in the LCM ( -1.3 mmol/l ) and TM ( -1.5 mmol/l ) than in the ADA ( -0.7 mmol/l ) , p = 0.001 . CONCLUSIONS An intensive 12-month dietary intervention in a community-based setting was effective in improving most modifiable cardiovascular risk factors in all the dietary groups . Only the LCM improved HDL levels and was superior to both the ADA and TM in improving glycaemic control BACKGROUND The effects of a carbohydrate-restricted diet on weight loss and risk factors for atherosclerosis have been incompletely assessed . METHODS We r and omly assigned 132 severely obese subjects ( including 77 blacks and 23 women ) with a mean body-mass index of 43 and a high prevalence of diabetes ( 39 percent ) or the metabolic syndrome ( 43 percent ) to a carbohydrate-restricted ( low-carbohydrate ) diet or  a calorie- and fat-restricted ( low-fat ) diet . RESULTS Seventy-nine subjects completed the six-month study . An analysis including all subjects , with the last observation carried forward for those who dropped out , showed that subjects on the low-carbohydrate diet lost more weight than those on the low-fat diet ( mean [ + /-SD ] , -5.8+/-8.6 kg vs. -1.9+/-4.2 kg ; P=0.002 ) and had greater decreases in triglyceride levels ( mean , -20+/-43 percent vs. -4+/-31 percent ; P=0.001 ) , irrespective of the use or nonuse of hypoglycemic or lipid-lowering medications . Insulin sensitivity , measured only in subjects without diabetes , also improved more among subjects on the low-carbohydrate diet ( 6+/-9 percent vs. -3+/-8 percent , P=0.01 ) . The amount of weight lost ( P<0.001 ) and assignment to the low-carbohydrate diet ( P=0.01 ) were independent predictors of improvement in triglyceride levels and insulin sensitivity . CONCLUSIONS Severely obese subjects with a high prevalence of diabetes or the metabolic syndrome lost more weight during six months on a carbohydrate-restricted diet than on a calorie- and fat-restricted diet , with a relative improvement in insulin sensitivity and triglyceride levels , even after adjustment for the amount of weight lost . This finding should be interpreted with caution , given the small magnitude of overall and between-group differences in weight loss in these markedly obese subjects and the short duration of the study . Future studies evaluating long-term cardiovascular outcomes are needed before a carbohydrate-restricted diet can be endorsed Context In 2003 , the authors reported that severely obese adults lost more weight and had better serum lipid patterns after 6 months of a low-carbohydrate diet rather than a conventional low-fat diet . Contribution After 1 year , these same patients still had more favorable triglyceride and high-density lipoprotein cholesterol levels on the low-carbohydrate diet than on the conventional diet . However , weight loss and the other metabolic parameters were similar in the 2 diet groups . Caution s The effect of the modest improvements in high-density lipoprotein cholesterol and triglyceride levels on the development of diabetes and cardiovascular disease is unknown . The Editors The prevalence of obesity and its associated metabolic abnormalities has increased markedly over the past 2 decades ( 1 , 2 ) . Although guidelines to follow a highcomplex carbohydrate , low-fat , energy-deficient diet to achieve weight loss are generally accepted ( 3 ) , considerable public interest has focused on low-carbohydrate diets ( 4 ) . We recently reported that persons with severe obesity lost more weight and had greater improvements in triglyceride levels , insulin sensitivity , and glycemic control after 6 months of a low-carbohydrate diet as compared with a conventional weight loss diet based on calorie and fat restriction ( 5 ) . However , these findings were preliminary because of the short duration of that study ( 6 ) . A simultaneously published study by Foster and colleagues suggested that persons on a low-carbohydrate 
    Output:
    
Similarly , non-weight loss trials and weight maintenance trials , for which there were no low-carbohydrate comparisons , had similar effects for low-fat vs moderate fat interventions , and were superior compared with “ usual diet ” .
Interpretation These findings suggest that the long-term effect of low-fat diets  on body weight depends on the intensity of intervention in the comparison group .
When compared to dietary interventions of similar intensity , evidence from RCTs does not support low-fat diets over other dietary interventions