Islamabad - Now, a new study sheds light on how the renin-angiotensin system - the hormone system that regulates blood pressure - may also promote excess weight gain. The discovery offers a potential target for obesity treatment. Uncovering new strategies to fight obesity is a key focus for researchers, given that the condition is a growing public health concern.

Senior study author Justin Grobe, PhD, assistant professor of pharmacology at the University of Iowa, and colleagues published their findings recently.

According to Grobe and colleagues, whether RAS promotes weight gain or weight loss depends on where in the body it is active. For example, if the RAS is highly active in the brain, it increases energy expenditure by boosting resting metabolism, which leads to weight loss.

However, If peripheral RAS activity is increased - that is, if there are high levels of the RAS hormone angiotensin circulating in the rest of the body - it reduces resting metabolism, causing weight gain. Heightened peripheral RAS is often found in obese individuals.  “At a very simplistic level, you can think of the brain RAS as the gas pedal on metabolism and the peripheral (circulating) RAS as the brake, with angiotensin as the driver,” explains Grobe.

For their study, Grobe and colleagues set out to investigate the mechanisms by which the peripheral RAS dampens resting metabolism, with the aim of bringing us closer to a strategy that could halt this process.  Subcutaneous fat refers to fat that is directly under the skin, and it is considered by some health professionals as a “healthy” fat. Visceral fat, however, which is stored deep in the abdominal area, is considered an “unhealthy” fat, raising the risk of obesity-related diseases, such as diabetes and heart disease.

Next, the team activated a receptor called angiotensin II type 2 (AT2) in the subcutaneous fat cells of the mice. AT2 is normally activated when the peripheral RAS is increased.  After the AT2 receptor was activated, the researchers found the mice gained weight, despite experiencing no changes in diet or food intake.

In detail, they found that AT2 activation lowers the production of a protein called UCP1 in subcutaneous fat cells, which is key for non-shivering thermogenesis. Lower UCP1 levels impair fat cells’ ability to generate heat, the team notes.

“If the fat cell is the thermogenic tissue (generating heat by burning calories), you can either have a bigger engine or you can push the gas pedal harder to create a larger effect,” explains Grobe. “Our study shows that angiotensin is modulating the size of the engine (amount of UCP1), not how hard the gas pedal is being pushed.”

Overall, the researchers say their findings suggest that increased peripheral RAS activity - through increased angiotensin levels - promotes obesity through AT2 activation and impaired thermogenesis.  “In multiple ways, activation of the AT2 receptor [by increasing the peripheral RAS] is interfering with the capacity of the cell to make heat.  It is very consistent with the clinical observation that peripheral angiotensin goes up during obesity. This is probably at least one of the mechanisms by which that excess angiotensin is perpetuating obesity. Because it is telling the body to slow down its metabolism as the body gets bigger.”

Justin Grobe, Ph.D. The authors say this increased understanding of how the RAS affects weight gain could pave the way for new treatments for obesity and its related complications.

Daily serving of pulses may aid long-term weight loss

Adding just one serving of pulses a day to the diet could help people lose weight and keep it off, concludes a new study. Eating just 130 g of pulses daily could help with weight loss, new research suggests.

The researchers found that people who ate 130 g of pulses every day for an average of 6 weeks lost weight, compared with those who did not eat pulses daily, even when they made no other notable dietary changes.

A part of the legume family, pulses include dried beans, dried peas, chickpeas and lentils.

Pulses are low in fat and high in protein and fibre, making them an ideal food choice for individuals who do not get protein from meat, fish or dairy products. They are also high in iron, zinc, phosphorus, folate and many other vitamins and minerals.

Numerous studies have documented the heath benefits of pulses. In 2014, for example, Medical News Today reported on a study suggesting a serving of pulses each day may lower “bad” low-density lipoprotein (LDL) cholesterol by 5%.

Now, new research suggests adding a daily serving of pulses to the diet could also help tackle overweight and obesity.

To reach their findings, lead author Dr. Russell de Souza, of the Li Ka Shing Knowledge Institute at St. Michael’s Hospital in Toronto, Canada, and colleagues conducted a meta-analysis of 21 clinical trials involving 940 participants.

These trials compared the weight-loss effects of diets containing dietary pulses with diets that did not, and each trial was conducted for a minimum of 3 weeks.

Over a median duration of 6 weeks, the team found that individuals who consumed 130 g (3/4 cup) of pulses daily had an average weight loss of 0.34 kg - just over half a pound - compared with people who did not eat pulses daily.

What is more, the team notes that the pulse-consuming individuals who experienced weight loss made no other major changes to their diets.

Previous research from Dr. de Souza and colleagues found that eating pulses can increase the feeling of fullness by around 31%, which they say may explain these latest findings.

Because pulses have a low glycemic index (GI), meaning they are broken down slowly, they make us feel full for longer, which can result in reduced food intake and weight loss.