Lone V. Nielsen, et al. Danmark och Kanada
Journal of Nutritional Science (2016), vol. 5, e22, page 1 of 7
The purpose was to determine the effect of an LCD diet in obtaining 8% weight loss in persons with serious obesity, faced with obesity surgery.
30 women and men between the ages of 18 and 65 with BMI >40 or BMI >35 kg/m2 with simultaneous sleep apnoea or hypertension.
Participants were divided into two groups of 15 people respectively, where one of the groups was operated on in week 8 and the other group in week 12. All participants took part in an LCD diet for 11 weeks. They were examined at the beginning of the study after 7 and 11 weeks, respectively. In this study, only the preoperative time from the beginning of the study up until week 7 for all participants, as well as the period from week 7 to 11 for group 2, were examined. The participants received nutritional advice from a dietician on a weekly basis.
The diet consisted of four powder-based meals, 1 litre of skimmed milk, 295 g of vegetables and 100 g of low-fat yoghurt, which provided 1030 kcal. The participants evaluated the side effects and their own adherence to the diet on a weekly basis when visiting the dietician. Adherence was graded on a scale between one and five, where five indicated extremely good adherence.
The average weight loss in week seven was 9.3%, which corresponds to 12.7 kg. 77% of patients reaching their preoperative target weight, and this was achieved, on average, during week 4 to 5. The average weight loss in this group was 10.2 % which corresponds to 14.1 kg. The other patients had gone down by 6.1% on average in week seven, which corresponds to 7.9 kg.
An analysis showed that the group of patients that had a high original weight also lost more weight in comparison with those patients who had a lower weight at the beginning of the study. The weight loss also consisted to a greater extent of fat-free mass in the group that had a lower original weight.
Blood fats were significantly reduced between the start of the study and week 7. No further improvement took place between week 7 and 11.
For the majority of study participants, it is possible to obtain a rapid preoperative weight loss of 8% percent during a 7-week LCD period. The reported adherence among patients was generally good during the seven weeks, and this recording also explained the 35% variation in weight loss among patients.
The number of patients that terminated during the course of the study was only 7%, which shows that treatment with an LCD regimen is a functioning method to achieve preoperative weight loss. Adherence had previously been shown to wane with time; however, in this study, adherence remained unchanged between week 7 and 11, which indicates that treatment with LCD for 11 weeks is reasonable.
It had previously been suggested that a loss of fat-free mass in obese patients should be between 20 to 30% of the total weight loss. In this study, the loss of fat-free mass was considerably higher, i.e. 41.6% of the total weight loss, in spite of a relatively high protein content in the diet (39 %). However, the question remains as to whether an LCD diet can be considered to be a protein-rich diet for obese patients. There are no formal recommendations concerning protein content for obese patients during weight loss. As the average protein intake in this study was 0.75 g per kilogram at the beginning of the study, an argument can be made that a protein intake under an LCD diet should not be considered high for this group. The large difference in energy balance that arises under an LCD diet in this patient category can be an underlying reason behind the high proportion of fat-free mass loss. This correlation has been shown in previous studies.
The blood values fell during the LCD diet, but the study showed no further improvement between week 7 and week 11. This indicates that the improvement in blood values has an immediate effect when energy is restricted.
The results of this study show that it is possible to achieve a preoperative weight loss of 8% with an LCD diet over the course of seven weeks. The weight loss that was achieved in week 7 resulted in an improved metabolic profile and lower blood pressure that was not affected further on until week 11, in spite of a weight loss of 3.9% during this period. The mechanisms behind the high loss of fat-free mass in seriously obese persons that go on the LCD diet need to be studied further.