Randomization to a low-carbohydrate diet advice improves health related quality of life compared with a low-fat diet at similar weight-loss in Type 2 diabetes mellitus

Aims: To compare the effects on health-related quality of life (HRQoL) 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. To describe different aspects of taking part in the intervention following the LFD or LCD.

Methods: Prospective, randomized trial of 61 adults with Type 2 diabetes mellitus. The SF-36 questionnaire was used at baseline, 6, 12 and 24 months. Patients on LFD aimed for 55-60 energy percent (E%) and those on LCD for 20 E% from carbohydrates. The patients were interviewed about their experiences of the intervention.

Results: Mean body-mass-index was 32.7 ± 5.4 kg/m2 at baseline. Weight-loss did not differ between groups and was maximal at 6 months, LFD: -3.99 ± 4.1 kg, LCD: -4.31 ± 3.6 kg, (p < 0.001 within groups). There was an increase in the physical component score of SF-36 from 44.1 (10.0) to 46.7 (10.5) at 12 months in the LCD group (p < 0.009) while no change occurred in the LFD group (p < 0.03 between groups). At 12 months the physical function, bodily pain and general health scores improved within the LCD group (p values 0.042-0.009) while there was no change within the LFD group.

Conclusions: Weight-changes did not differ between the diet groups while improvements in HRQoL only occurred after one year during treatment with LCD. No changes of HRQoL occurred in the LFD group in spite of a similar reduction in body weight.

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Alex’s Notes: Arguably, the best diet is the one that you can stick with. While most studies comparing low-fat to low-carbohydrate diets, including the one at hand, have found similar weight loss outcomes, other factors affecting health may differ between the two. In diabetics, for example, it has been demonstrated that a diet of 50/20/30 FAT/CHO/PRO is superior to an isocaloric 30/55/15 diet for blood glucose regulation in type-2 diabetics despite identical weight-loss. In the current study, the authors took the data from the previously mentioned study in diabetics and compare effects on health-related quality of life in the participants.

“The patients were randomized either to a low-carbohydrate diet or to a traditional low-fat diet, both with a caloric content of 1600 kcal for women or 1800 kcal for men… The low-carbohydrate diet had an energy content where 50 E% was fat, 20 E% carbohydrates and 30 E% protein. The low-fat diet had a nutrient composition that was similar to what is traditionally recommended for treatment of Type 2 diabetes in Sweden with 30 E% fat (less than 10 E% saturated fat), 55-60 E% carbohydrates and 10-15 E% protein. No information was given to change the level of physical activity of the participants.”

Overall, the study had recruited 61 men and women with an average age of 62-years and average diabetes duration of 9.5-years. The generic Short Form-36 (SF-36) questionnaire designed to measure individuals HRQoL was administered at baseline, 6-, 12-, & 24-months. As mentioned, the weight loss between the groups was not different at any time point.

By 6-months, there were no changes in any of the SF-36 domains from baseline for either group. However, at 12-months the low-carb group showed significant improvements in “physical function,” “bodily pain,” “vitality,” and the combined “Physical Component Score (PCS),” while the low-fat group continued to lack any changes. At 24-months neither group had any significant changes from baseline. Interestingly, the changes in PCS for the low-fat group only was inversely associated with changes in BMI and HbA1c, and there were no associations between regain of body weight from 6 to 12 months and changes of SF-36 variables. For completeness I included the weight change in the table below.






Weight-change (kg)





In addition to the SF-36, the researchers interviewed the participants regarding different aspects of taking part of the intervention following the low-fat or low-carbohydrate diet. Their thoughts are summarized in the table below.



Potatoes hard to restrain from as well as change from low-fat to high-fat products.

Difficult to substituted pasta, potatoes, cookies, and snacks.

Hard to eat so much fatty products.

Felt less hungry and were less prone to sweets.

Changes not burdensome.

Wanted more dietary variety.

Felt Guilty when not strictly following diet.

Diet was described as easy to follow, tasty and cheap in price.

Difficulties when eating in other people's homes or when going to restaurants and during holidays. Strategies mentioned were to eat very little of the food not allowed. During Christmas it was easy to find alternatives to eat.

Supportive if the whole family could follow the same diet. In the low-carbohydrate group the families sometimes choose to prepare two different meals at a time.

So at the end of the day, the researchers found that after 12 months, improvements of HRQoL were found only in the low carbohydrate group, and that they related to physical function, vitality, and general health, while the domains relating to mental health showed no change. There could be many reasons for these improvements, including weight-loss or improved glycemic control, but the fact that there were no changes in the SF-36 at six months when weight loss was greatest argues against the improvements being a result of only weight loss. Perhaps it was just the change in macronutrients and foods choices. Regardless of the outcomes of this study, the main reason I wanted to share it with you was to remind us both that there is more to diets than weight. It must be sustainable and enjoyable.


0 # ChrisDopp 2015-07-15 05:15
A recently published study investigated some of the factors that affect quality of life in patients with diabetes and made several notices. The noticed that physical activity is important for patients and it has an impact on their quality of life. Besides, they noted that the kind of treatment the patient is taking has an impact on his quality of life. Education and relationship is among other factors that affect patients’ quality of life.
The full study could be reached here

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