Weight Loss Diet Study: Low Carb vs Low Fat

Not Recruiting

Trial ID: NCT01661426


The traditional weight loss diet recommended by health professionals has been a low-fat, high-carbohydrate, calorie restricted diet. This recommendation has been challenged by a number of alternative dietary strategies, particularly low-carbohydrate diets. In several recent weight loss studies insulin resistant adults had more success with low- vs. high-carbohydrate diets, in contrast to insulin sensitive adults who had either more success or comparable success with the low-fat diets. The investigators enrolled 61 people with a wide range of insulin sensitivity/resistance. After determining their insulin resistance status, the investigators will split them in the middle and randomly assign them to one of four groups for six months: (1) Low-Carbohydrate/Insulin Resistant (LC/IR); (2) Low-Carbohydrate/Insulin Sensitive (LC/IS); (3) Low-Fat/Insulin Resistant (LF/IR); and (4) Low-Fat/Insulin Sensitive (LF/IS) (15 people/group). After 6 months the participants will switch diet for the following 6 months, i.e. those randomized to the Low-Carbohydrate diet will switch to the Low-Fat diet and vice-versa. The primary outcome of this study is to determine whether weight loss success can be increased if one follows the dietary approach appropriately matched to their insulin resistance status. Secondary outcomes include fasting insulin, glucose, lipids, and fatty acid composition. --------------------------------------------------------------------------------

Official Title

Weight Loss Diet Study: Low Carbohydrate vs. Low Fat and Insulin Resistance Status

Stanford Investigator(s)


Inclusion Criteria:

* Age: \> or = 18 years of age
* Women: Pre-menopausal (self-report) and \<50 years of age
* Men: \<50 years of age
* Race/Ethnicity: All
* BMI (body mass index): 28-40 kg/m2 (need to lose \>10% body weight to achieve healthy BMI)
* Body weight stable for the last two months, and not actively on a weight loss plan
* No plans to move from the area over the next 14 months
* Available and able to participate in the evaluations and intervention for the study period
* Willing to accept random assignment
* To enhance study generalizability, people on medications not noted below as specific exclusions can participate if they have been stable on such medications for at least three months
* Ability and willingness to give written informed consent
* No known active psychiatric illness

Exclusion Criteria:

* Pregnant, lactating, within 6 months post-partum, or planning to become pregnant in the next 12 months; no menstruation for the previous 12 months
* Diabetes (type 1 and 2) or history of gestational diabetes or on hypoglycemic medications for any other indication
* Prevalent diseases: Malabsorption, renal or liver disease, active neoplasms, recent myocardial infarction, hypertension (except for those stable on hypertensive medications) (\<6 months) (patient self-report and, if available, review of labs from primary care provider)
* Smokers (because of effect on weight and lipids)
* History of serious arrhythmias, or cerebrovascular disease
* Uncontrolled hyper- or hypothyroidism (TSH not within normal limits)
* Medications: Lipid lowering, diabetes medications, and those known to affect weight/energy expenditure
* Excessive alcohol intake (self-reported, \>3 drinks/day)


behavioral: Low-Carbohydrate Diet

behavioral: Low-Fat Diet

Not Recruiting

Contact Information

Stanford University
School of Medicine
300 Pasteur Drive
Stanford, CA 94305
Antonella Dewell