ISLAMABAD - Want to stay slim? Make sure that you eat enough protein in your diet, rather than simply cutting calories, says a new study.

Researchers at the University of Sydney have carried out the study and found that low protein in diets can lead to excessive energy intake and drive people to eat more snacks, the `PLoS ONE` journal reported.

On the contrary, they have found that enough protein in their diets help people in curbing appetites and preventing excessive eating of fats and carbohydrates.

The results represent the first scientifically supported evidence that dietary protein plays an important role in appetite and total food consumption in humans, and are an important step in addressing the global obesity epidemic.

"Humans have a particularly strong appetite for protein, and when the proportion of protein in the diet is low this appetite can drive excess energy intake.

"Our findings have considerable implications for body weight management in the current nutritional environment, where foods rich in fat and carbohydrates are cheap, palatable, and available to an extent unprecedented in our history," lead author Dr Alison Gosby said.

Protein is the driving force for appetite in many animals, according to the researchers.

Although it has previously been suggested that protein content plays an important role in determining overall energy intake in humans, and is therefore linked to obesity, until now experimental verification has been lacking.

In their study, the researchers wanted to test the `protein-leverage` effect in humans. So, they created three menus that represented low (10 percent), intermediate (15 percent) and high (25 percent) protein, based on data from the World Health Organisation recommending people eat 15 percent protein diets.

The researchers then took a group of 22 lean people and fed each subject each of the three menus during three separate four-day periods, monitoring energy intake over each four-day period and hunger ratings on day four.

They found subjects who ate a 10 percent protein diet consumed 12 per cent more energy over four days than those eating a 15 percent protein diet. Moreover, 70 percent of the increased energy intake on the lower protein diet was attributed to snacking.

When the protein content was further increased to 25 percent, however, the researchers observed no change in behaviour relative to the 15 percent protein diet. On the fourth day of the trial, however, there was a greater increase in the hunger score between one to two hours after the 10 per cent protein breakfast versus the 25 per cent protein breakfast.

Dr Gosby said: "This result confirms the protein-leverage effect in humans and importantly, shows counting calories is not enough to manage appetite and body weight."

Exercise may not limit

pregnaNcy weight gain:

Exercising during pregnancy was safe for both moms and babies in a new study of heavy women in Brazil, but fitness classes and at-home exercises didn`t keep moms-to-be from gaining too much weight.

The finding is "not surprising," according to Dr. Patrick Catalano, a maternal-fetal medicine researcher from Case Western Reserve University School of Medicine in Cleveland.

"Lots of studies have not shown any benefits relative to weight gain in pregnancy using either diet or exercise," said Catalano, who didn`t participate in the new research.

The US-based Institute of Medicine recommends that overweight women should gain between 15 and 25 pounds during pregnancy, and obese women 11 to 20 -- less than the amount recommended for normal-weight women.

Being overweight or obese while pregnant, or gaining too much weight during pregnancy, increases the chance of having a large baby and needing a Caesarean section. It also ups the risk that babies will have birth defects or grow up to be obese, researchers said.

Plus, women who gain a lot of weight during pregnancy tend to keep in on afterwards, Catalano told a news agency.

He said that starting an exercise or diet program mid-way through pregnancy probably isn`t as useful as intervening very early in pregnancy -- or better yet, before.

 In the current study, researchers led by Simony Nascimento from UNICAMP Medical School in Campinas recruited 82 heavy women who were already between three and five and a half months into their pregnancies.

They split those women into two groups. Half went to weekly exercise classes and got counselled on nutrition, weight gain and home exercises or walking they could do daily. The other women received standard prenatal care advice, but no extra information on exercise.

Regardless of whether they were assigned to do group and at-home exercise, about half of the women gained more weight than recommended upper limits.

On average, obese women gained 23 to 24 pounds in both groups. Overweight women gained an average of 22 pounds when they exercised and 36 when they didn`t, but the researchers caution that those findings were based on a small group of only 14 women.

The majority of all babies were born by c-section, but there was no difference in their health at birth based on whether or not moms exercised, Nascimento and colleagues report in BJOG: An International Journal of Obstetrics and Gynaecology.

Catalano said the findings don`t take away from the fact that, "moderate exercise is very good, no question about it." But he said that the farther women get into pregnancy, the harder it is for them to stick to an exercise program. That`s why starting with exercising and diet improvement early is so important.

One of the problems is that historically, women have been given the wrong message about eating and physical activity in pregnancy, said Dr. Raul Artal, head of obstetrics, gynaecology and women`s health at Saint Louis University School of Medicine.

"Pregnancy is not a state of confinement and indulgence. It`s an ideal time for behavioural modification for the benefit of both mother and the baby," Artal, who wasn`t involved in the new research, said.

He considers pregnancy an opportunity to address unhealthy behaviours in patients. "In general women are more prone to adopt healthy lifestyles in pregnancy because of the concern for the unborn child."

Nascimento`s team also pointed out that women typically have more contact with health providers when they`re pregnant.

But, Artal added, "The sad thing is that as a society we have become more sedentary and more overweight and obese. This is not confined to pregnant women."

The researchers recommended 30 minutes of moderate exercise each day for overweight and obese pregnant women, along with stretching and nutrition counselling.