June 8, 2011

Fat Cells & Obesity

(Ivanhoe Newswire)-- Millions of adults are diagnosed with obesity each year, but how do fat cell membranes adapt to this high body mass index? A study led by Matej Oresic, from VTT Technical Research Center of Finland, suggests that adaptation of fat cell membranes to obesity may play a major role in early stages of inflammatory disorders.

Many of those diagnosed with obesity suffer from a disorder known as metabolic syndrome which includes symptoms such as hypertension and elevated blood cholesterol. They are also at risk of developing additional diseases such as heart disease and diabetes mellitus. Antonio Vidal-Puig, from the University of Cambridge, Matej Oresic and colleagues used lipidomics, the large scale study of pathways and networks of cellular lipids in biological systems, to study the fat tissue biopsies among several sets of twins.

Monozygotic twins were used for the study because they share the same DNA and early upbringing, accounting for the impact of certain factors on adult body mass phenotypes while leaving other factors such as diet and lifestyle choices as the major variables.  In each twin pair, one twin was obese while the other exhibited a normal body mass index. Men are considered obese is they have more than 25 percent body fat and women if they are more than 30 percent.

Researchers found that the obese twins had lower amount of polyunsaturated fatty acids in their diet. Fatty acids supply energy for the muscles, heart, and other organs. Polyunsaturated fatty acids are "good" fatty acids providing many health benefits when used to replace saturated fatty acids. Unexpectedly, the study found that obese people had higher amounts of certain types of lipids containing polyunsaturated fatty acids in their adipose tissues than their non obese twin.

This finding is interesting because cell membranes are primarily composed of lipids which can alter the membranes physical properties such as fluidity. The author's of the study found that the new lipids observed in the cells of the obese twins, balanced each other in a way that overall membrane fluidity was unaffected. The authors concluded that the lipid-content changes in obese individuals might be an adaptation to preserve membrane function as the cells expand. However, this adaptation can only go so far and breaks down in those who are morbidly obese.

Data points to some of the mechanisms that the body may use to adapt to excess fat. These results may also explain why obese people are at risk of developing inflammatory disorders. These findings, while needing to be validated in further studies, represent a valuable angle to approach this problem.

SOURCE: PLos Biology, June 6, 2011