A study of 92 adolescents conducted in Brazil suggests girls are more likely than boys to develop metabolic alterations associated with obesity, such as high blood pressure and dyslipidaemia. The study was conducted with Fundação de Amparo à Pesquisa do Estado de São Paulo’s (FAPESP) support by scientists affiliated with the University of São Paulo's Biomedical Sciences Institute (ICB-USP) and the Medical School of Santa Casa de Misericórdia de São Paulo (FCM-SCMSP). The findings are reported in an article, ‘Sex-Dependent Dyslipidemia and Neuro-Humoral Alterations Leading to Further Cardiovascular Risk in Juvenile Obesity’, in the journal Frontiers in Nutrition. According to the authors, girls with obesity displayed a pattern of lipid profile alterations not seen in girls without obesity and a higher propensity to develop cardiovascular disease in adulthood.
"We found that girls have a much greater tendency to undergo the alterations typical of obesity, such as elevated blood pressure and dyslipidaemia,” said Dr Estefania Simoes, first author of the article. “In our study, they had augmented levels of triglycerides and LDL, while HDL was lower than in eutrophic [normal weight] girls.”
The lipid profile of the obese boys included in the study displayed no significant differences from that of normal-weight boys, according to the researchers.
A substantial amount of research shows this, but the differences between boys and girls in terms of the effects of obesity have not been studied in depth.
"We compared obese and non-obese girls and boys aged 11-18, simultaneously addressing anthropometrics, lipid and lipoprotein profile, and hormone and neuropeptide levels, with a special emphasis on sex-dependent responses. To our knowledge, this is the first study to take this multifactor approach," Simoes explained.
The study was funded by FAPESP via two projects: "Cerebral anatomy, inflammatory mediators and appetite regulatory hormones in obese pediatric patients: A neurobiological study of obesity" and "Systemic inflammation in cachectic cancer patients: Mechanisms and therapeutic strategies, a translational medicine approach."
The study was conducted in collaboration with Ricardo Riyoiti Uchida, a neurologist and psychiatrist who acted as principal investigator and recruited the 92 participants at the Child Obesity Outpatient Clinic of the Santa Casa de Misericórdia Hospital in São Paulo. Uchida uses neuroimaging to try to find out whether there are alterations in the brain regions associated with satiety and appetite in obese subjects.
The SCMSP team took the subjects' blood pressure and collected blood samples to measure fasting serum concentration of total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), very-low-density lipoprotein cholesterol (VLDL), and triglycerides (TG).
The researchers also looked for binge eating patterns and addiction to high-sugar and high-fat foods using special-purpose questionnaires. They also measured neuropeptides linked to neuro-humoral alterations and detected significant alterations in obese subjects. Neuropeptides are released in response to peripheral signals such as hormones to regulate appetite and energy balance.
"In addition, leptin and insulin interact with neuropeptides NPY, MCH and a-MSH, not only regulating appetite but also activating the sympathetic nervous system, which may contribute to the high blood pressure associated with obesity," added Simoes.
The new data on differences between girls' and boys' hormone, cytokine and neuropeptide profiles points to the need for personalized treatment.
"However much we may want to design a single therapeutic strategy based on drugs or food supplements, our findings show that girls and boys shouldn't be treated alike even if they have the same weight and age, because their organisms respond to treatment differently.”
"At the laboratory headed by Professor Marília Seelaender, a co-author with us of both articles, we've long been studying a disorder that's the opposite of obesity: cachexia [extreme weight loss and muscle wasting, frequently in cancer and AIDS patients]. Systemic inflammation plays a key role in both," said Joanna Correia-Lima, second author of the article. "We first focused on inflammation and then on the role of hormones and how they relate to the predisposition to develop cardiovascular disease."
Most scientific publications on childhood obesity, she added, focus on a single specific alteration, such as inflammation or a hormone, for example, or on a specific consequence of obesity such as high blood pressure.
"Our research set out to connect the dots. We have a large cohort and a large amount of data, so we can characterize the links in this group, showing how all alterations in the obese organism are associated. The most important aspect of our work is showing these links. Elevated levels of hormones such as insulin and leptin may be the cause of high blood pressure, for example. This kind of information should be taken into consideration when treating obesity. Physicians often prescribe anti-inflammatory drugs, which can indeed mitigate one aspect of the disease, but the treatment will be more complete if you know about other contributing factors."
"Questionnaire-based assessments point to eating disorders at the psychological level among these girls and boys," concluded Simoes. "However much we show that there are alterations in neuropeptides and hormones, as well as high blood pressure, inflammation and so on, ultimately the child doesn't just have an organic problem but a psychological one. Hence the importance of childhood obesity studies, to assist early diagnosis and attempt timely treatment before adult complications set in."