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Low-carb diet causes more better results after one-year than low-fat: 11 lbs vs 7 lbs
Monday, October 25, 2010 9:50 am Email this article
"Participants on a low-carbohydrate diet had more favorable overall outcomes at one-year than did those on a conventional [low-fat] diet," concludes a new study conducted at the Philadelphia Veterans Affairs Medical Center. People who were assigned to follow a low-carb diet maintained a weight loss of 11.2 pounds after one-year compared to a weight loss of 6.8 pounds for people who were assigned to follow a low-fat diet. The difference in weight loss between the groups was not statistically significant, however there still was an 80 percent chance that this difference in weight loss was due to the diet. Some articles have concluded that this study shows that low-carb diets are no better than low-fat diets, however this was not the conclusion of the study. Weight Loss
Weight Loss: Low-Carb Group Lost In 6 Months; Low-Fat Throughout The Year
People in the low-carb group maintained most of weight they had lost after six months, whereas people in the low-fat group continued to lose weight throughout the year.
Calorie Intake: Low-Carb: 1462; Low-Fat: 1822
The low-carb group ate fewer calories than the low-fat group: 1462 calories per day versus 1822.
Protein Intake: Same In Both Groups: 73-74 Grams
Both groups ate 73-74 grams of protein per day.
Carbohydrate Intake: Low-Carb: 120 Grams; Low-Fat: 230 Grams
The low-carb group ate an average of 120 grams of carbohydrates per day compared to 230 grams for the low-fat group.
Fat Intake: Low-Carb: 93 Grams; Low-Fat: 69 Grams
The low-carb group consumed an average of 93 grams of fat per day compared to 69 grams for the low-fat group.
Fiber Intake: Low-Carb: 7 Grams; Low-Fat: 12 Grams
The low-carb group consumed an average of 7 grams of fiber per day compared to 12 grams for the low-fat group. This is much lower than the 20-35 grams per day as recommended by the American Dietetic Association.
The National Academies of Sciences says that, based on the amount of fiber intake shown to protect against coronary heart disease, an adequate intake of fiber for young women is 25 grams per day, and young men 38 grams per day.
HDL Levels Were Maintained Better On The Low-Carb Diet
HDL levels were better maintain in the low-carb group than the low-fat group: -1 mg/dL versus -5 mg/dL. HDL levels in the low-carb group dropped from 41 mg/dL at the start of the study to 40 mg/dL at the end of one-year.
LDL Levels: No Significant Difference Between Groups
LDL levels increased by 7 mg/dL in the low-carb group, from 112 to 120 mg/dL, and decreased by 4 mg/dL in the low-fat group from 121 to 118 mg/dL. (Rounding causes the apparent difference in subtraction that you see.)
Triglycerides Decreased More On The Low-Carb Diet: -58 Mg/Dl Vs +4
Triglycerides dropped much more in the low-carb group than the low-fat group: -58 mg/dL versus +4 mg/dL.
Insulin Levels: Low-Carb: -49 Pmol/L; Low-Fat: +14
In people without diabetes, insulin levels dropped by 49 pmol per liter in the low-carb group, from 153 to 104, compared to an increase of 14 pmol per liter in the low-fat group, from 160 to 174, however, because a wide variations in readings, the difference was not statistically significant.
In people with diabetes, insulin levels dropped by 35 pmol per liter in the low-carb group, from 292 to 257, compared to a drop of 28 pmol per liter in the low-fat group, from 229 to 201.
Insulin Sensitivity: No Difference Between The Groups
There was no significant difference in insulin sensitivity between the groups. Both groups maintained an insulin sensitivity of 31-32.
Diabetes Better Controlled On The Low-Carb Diet
Hemoglobin A1C levels (HBA1C), a marker to determine the long-term control of diabetes, improved more for people on the low-carbohydrate diet.
Hemoglobin A1C levels dropped in the low-carb group from 7.4 to 6.6 percent compared to a drop from 7.3 to 7.3 percent in the low-fat group.
The normal level for hemoglobin A1C is less than 7 percent. Diabetics rarely achieve such levels, but tight control aims to come close to it. Levels above 9 percent show poor control, and levels above 12 percent show very poor control.
The Diabetes Control and Complications Trial (DCCT) showed that diabetics who keep their hemoglobin A1C levels close to 7 percent have a much better chance of delaying or preventing diabetes complications that affect the eyes, kidneys, and nerves than people with levels 8 percent or higher.
A change in treatment is almost always needed if the level is over 8 percent.
Lowering the level of hemoglobin A1C by any amount improves a person’s chances of staying healthy.
These metabolic advantages a low-carbohydrate diet remained even after adjusting for the differences in weight loss between the groups. In other words, a low-carbohydrate has has advantages beyond just weight loss.
Randomly Assigned to Diets
People Randomly Assigned To Low-Carb Or Low-Fat Group
People were randomly assigned to either a low-carbohydrate diet or a low-fat diet.
Uric Acid Levels
Uric Acid: Low-Carb: +17 Mmol/L; Low-Fat: -12
Uric acids levels increased by 17 mmol per liter in the low-carb group, from 381 to 399, and decreased by 12 mmol per liter in the low-fat group from 399 to 387.
Blood Pressure: No Significant Change
Diastolic blood pressure increased from 77 to 80 mmHg in the low-carb group compared to an increase from 82 to 83 mmHg in the low-fat group. The changes were not significant.
Systolic blood pressure increased from 133 to 134 mmHg in the low-carb group compared to an increase from 139 to 142 mmHg in the low-fat group. The changes were not significant.
The Low-Carb Diet: Less Than 30 Grams of Carbs Per Day
The low-carbohydrate diet consisted of limiting carbohydrate intake to less than 30 grams per day.
Note that there were no calorie restrictions placed on this group.
The Low-Fat Diet: Less Than 30% Of Calories From Fat
The low-fat diet was designed to be 500 calories per day less than a person???s needs and they were to consume less than 30 percent of calories from fat.
Monthly Groups Sessions For Both Groups
Both groups had weekly group sessions for the first month, followed by monthly group sessions for the remaining eleven months.
The study involved 132 severely obese adults, at least 18-years-old, with a body mass index of 35 or more.
Eighty-three percent of the subjects had diabetes or the metabolic syndrome, also known as Syndrome X.
Dropouts: 20 People In The Low-Carb Group; 25 People In The Fat Group
Twenty people in the low-carb group and twenty-five people in the low-fat group had dropped out the study after one-year.
The dropouts tended to be younger on average than the group as a whole.
On average people who dropped out the low-carb group had lost almost no weight, only 0.4 pounds. I would guess that they dropped out because they did not stick with the diet and therefore did not lose weight.
Stern L, Iqbal N, Seshadri P, Chicano KL, Daily DA, Mcgrory J, Williams M, Gracely EJ, Samaha FF. 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 May 18, 140(10):778-85.
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