SWEET partners have published a recent article in the journal Obesity which has been selected as Editor’s Choice. The research represents a sub-study of SWEET WP3. We were pleased to interview lead author Michelle Pang to discuss the paper, The effect of weight loss on whole-body and tissue-specific insulin sensitivity and hepatic lipid content and composition: SWEET substudy

Great to connect Michelle, and congratulations on your new publication in Obesity and its selection as Editors Choice.

Let’s start with an explanation of the central premise of your paper in layman’s terms.

The central premise is that weight loss has been shown to reduce the amount of fat in the liver(that is, intrahepatic lipid (IHL) content) and improve whole-body insulin sensitivity in people with overweight or obesity. Interestingly, recent findings suggest that the types of lipids (i.e., saturated versus unsaturated) present in the liver, rather than the total amount of liver fat, may play a crucial role in influencing insulin sensitivity. Unfortunately, there is a scarcity of human studies exploring this relationship.

What inspired you and the team to focus on the effects of LED-induced weight loss on insulin sensitivity and IHL content?

Due to the growing prevalence of obesity and its related metabolic disorders, it is important to better understand the mechanisms involved in the effects of weight loss on metabolic health, including insulin sensitivity and liver fat content. Numerous studies have demonstrated that weight loss improves insulin sensitivity and liver fat content. However, less is known about the effects that weight loss may have on the fatty acid composition in the liver after, as well as its association with changes in tissue-specific insulin sensitivity.

How did you select participants for your study?

Fifty individuals who participated in Work Package 3 intervention study of the European SWEET project underwent measurements to determine hepatic and skeletal muscle insulin sensitivity (by a 7-point oral glucose tolerance test) and liver fat content (by proton-magnetic resonance spectroscopy) at Maastricht University, the Netherlands.

Can you explain the wider significance of your finding that LED-induced weight loss significantly reduced body weight, waist and hip circumference, total body fat, and various fat masses?

Obesity, in particular abdominal obesity, acts as a gateway to numerous other chronic diseases, including cardiovascular disease, type 2 diabetes, and various types of cancers. By achieving weight loss, improving body composition, and lowering fat storage in non-adopose tissues such as the muscle and liver, individuals can reduce their risk of these diseases and improve their overall health and quality of life. Decreased body fat can enhance insulin sensitivity, blood lipid profiles, and glucose metabolism, which are important factors in preventing or managing conditions such as insulin resistance and the metabolic syndrome.

Please discuss the impact of LED-induced weight loss on hepatic and whole-body insulin sensitivity a bit with our readers. Why is this significant?

Our findings show that LED-induced weight loss improves whole-body and liver insulin sensitivity. As we know for many years already, this indicates that weight loss has important clinical implications for managing conditions like type 2 diabetes. By understanding and harnessing these effects, individuals can work towards achieving long-term improvements in metabolic health.Furthermore, examining tissue-specific effects of certain interventions helps identify in which organs or tissues beneficial effects are taking place, and whether this occurs in all people or only in certain subgroups of the population. This knowledge will help in guiding the development of more personalized interventions.

How does your research extend findings from previous studies that have looked into weight loss and IHL content?

To our knowledge, this study is the first to examine the fatty acid composition in the liver, by using proton-magnetic resonance spectroscopy, in individuals with overweight or obesity before and after LED-induced weight loss. We now demonstrate that weight loss decreases IHL content as well as the amount of saturated fatty acids in the liver. The decrease in IHL content was associated with weight loss-induced improvement in hepatic insulin sensitivity in individuals with overweight or obesity. Notably, on average, our study population showed a normal amount of fat in their liver (less than 5%) at baseline (i.e. before weight loss). This means that even individuals without excessive accumulation of liver fat can experience significant improvements in liver fat content through weight loss.

How do you see these findings affecting future treatment or interventions for people with overweight or obesity? Are there any immediate applications of your findings?

The present findings contribute to a better understanding of the changes in liver fat content and composition in relationship to whole-body and tissue-specific insulin sensitivity after weight loss in individuals with overweight or obesity. Furthermore, by examining the effects of weight loss on tissue-specific insulin sensitivity, researchers can identify specific tissues or pathways that may be particularly responsive to weight loss interventions. This knowledge can guide the development of targeted therapies or lifestyle interventions aimed at improving insulin sensitivity in key metabolic tissues, potentially leading to more effective and personalized treatments for metabolic disorders.