When people change their diets for what they think is the better, they usually have some aim in mind such as weight loss (the usual one) or improved health and wellbeing. Making dietary changes can, however, involve time and effort, not to mention a sense of sacrifice and/or deprivation. Obviously, for changes to be sustainable, it helps for any downside of a diet to be outweighed by the perceived benefits.
One way the global impact of any change in regime (e.g. dietary, exercise, sleep-related) can be assessed is to measure what is known as the ‘health-related quality of life’ (HRQoL). Specially designed questionnaires are available for this purpose that may encompass both physical and emotional aspects of health and wellbeing.
In a recent study, the HRQoL was assessed in two groups of dieters. One of these was put on a very low carbohydrate diet (think ‘Atkins’). While the other ate a low fat diet. The trial lasted for 24 weeks. Overall, quality of life that related to physical aspects of health improved in both groups, and there was no significant difference between the groups (except for bodily pain, which improved more in the low-fat group).
However, there was a distinct difference between the groups when it came to mental aspects of quality of life: overall, the low-carb group saw benefits here that were not seen in the low-fat group.
The authors of this study speculate on what it is about the low-carb diet that leads to improved mental wellbeing. One possibility here, is that the low-carb diet did not ask individuals to restrict how much they ate. Low carb diets also tend to promote satiety more than low-fat ones. Basically, a low carb diet is less likely to lead to individuals feeling hungry and/or deprived than a low-fat one.
Whatever the precise explanation, though, the most important thing is that from a mental perspective, individuals felt better on the low-carb diet. This has important immediate implications for mental wellbeing. In the long term, though, this benefit of low-carb eating might make this way of eating more sustainable and effective.
Yancy WS Jr, et al. Effects of two weight-loss diets on health-related quality of life. Qual Life Res. 2009 Feb 11. [Epub ahead of print]