Background: Many Norwegians have embraced the low-carb trend and choose butter and bacon instead of brown bread and carrots. This entails a dramatic change in the total intake of fat and the intake of saturated fat. We have investigated how a low-carb diet can affect the lipid profile in healthy adults with a normal bodyweight.
Material and method: Seven healthy female participants with normal bodyweight underwent a four-week trial of a low-carb diet (< 20-25 grams of carbohydrates/day). Daily diet registrations were made during the trial period, and diet data for three randomly selected days were included in the estimates. Blood samples and weight data were collected as fasting values prior to and after the intervention.
Results: Standardised diet data were available for six participants. On a low-carb diet, the energy intake from carbohydrates accounted for a median of 3 (spread: 2-5) per cent of the total energy intake. The intake of fat accounted for 71 (67-78) per cent of total energy, while protein accounted for 26 (19-31) of total energy intake. At baseline, the median value of total cholesterol was 4.1 mmol/L (dispersion: 3.3-5.7) and LDL cholesterol was 2.2 (1.8-3.4) mmol/L. The values increased to 5.2 (3.7-8.8) mmol/L and 3.1 (1.9-6.2) mmol/L for total and LDL cholesterol respectively. The absolute changes correspond to a percentage increase in total cholesterol of 33 (14-71)% and in LDL cholesterol of 41 (9-84)%. Median weight change amounted to -1.2 kg (-2.8-0.6).
Interpretation: A diet with little carbohydrate and a great deal of protein and fat resulted in a considerably heightened level of total cholesterol and LDL cholesterol in young, healthy women with a normal bodyweight. The findings indicate that a low-carb diet may have a negative impact on individual risk profiles. However, the study is small-scale and the results must be interpreted with caution.