Which is better, a low-fat/high-carbohydrate diet or a high-fat/low-carbohydrate diet — or is it the type of fat that matters? In a new paper featured on the cover of Science magazine’s special issue on nutrition, researchers from Harvard T.H. Chan School of Public Health, Boston Children’s Hospital, and colleagues with diverse expertise and perspectives on the issues laid out the case for each position and came to a consensus and a future research agenda.

The researchers agreed that no specific fat to carbohydrate ratio is best for everyone, and that an overall high-quality diet that is low in sugar and refined grains will help most people maintain a healthy weight and low chronic disease risk, medicalxpress.com reported.

“This is a model for how we can transcend the diet wars,” said lead author David Ludwig, professor in the Department of Nutrition at Harvard Chan School and a physician at Boston Children’s Hospital. “Our goal was to assemble a team with different areas of expertise and contrasting views, and to identify areas of agreement without glossing over differences.”

The authors laid out the evidence for three contrasting positions on dietary guidelines for fat and carbohydrate consumption:

1. High consumption of fat causes obesity, diabetes, heart disease, and possibly cancer, therefore low-fat diets are optimal.

2. Processed carbohydrates have negative effects on metabolism; lower-carbohydrate or ketogenic (very low-carbohydrate) diets with high fat content are better for health.

3. The relative quantity of dietary fat and carbohydrate has little health significance — what’s important is the type of fat or carbohydrate source consumed.

They agreed that by focusing on diet quality — replacing saturated or trans fats with unsaturated fats and replacing refined carbohydrates with whole grains and nonstarchy vegetables — most people can maintain good health within a broad range of fat-to-carbohydrate ratios.

Within their areas of disagreement, the authors identified a list of questions that they said can form the basis of a new nutrition research agenda, including:

1. Do diets with various carbohydrate-to-fat ratios affect body composition (ratio of fat to lean tissue) regardless of caloric intake?

2. Do ketogenic diets provide metabolic benefits beyond those of moderate carbohydrate restriction, and especially for diabetes?

3. What are the optimal amounts of specific types of fat (including saturated fat) in a very-low-carbohydrate diet?

Finding the answers to these questions, the researchers said, will ultimately lead to more effective nutrition recommendations.

If you are unable to exercise, a hot water treatment may help improve inflammation and blood sugar (glucose) levels, particularly in overweight men, suggests a new study.

Physical stress such as exercise can increase the level of an inflammatory chemical (IL-6), which activates the release of anti-inflammatory substances to combat unhealthily high levels of inflammation, known as chronic low-grade inflammation.

However, a hot-water immersion may “improve aspects of the inflammatory profile and enhance glucose metabolism in sedentary, overweight males and might have implications for improving metabolic health in populations unable to meet the current physical activity recommendations”, said researchers including Christof Andreas Leicht from the Loughborough University in the UK.

For the study, published in the Journal of Applied Physiology, the team included a group of sedentary, overweight men who participated in both hot-water immersion and ambient room temperature (control) trials separated by at least three days.

In the hot water trial, the volunteers sat immersed up to their necks in 102-degree Fahrenheit water. The research team measured the men’s heart rate, blood pressure and body temperature every 15 minutes throughout both the control and immersion conditions. Blood samples were taken again two hours after each session.

The researchers found that a single hot-water immersion session causes the elevation of IL-6 levels in the blood and increased nitric oxide production, but did not change the expression of heat shock protein 72 — another protein suggested to be important for health.

However, a two-week treatment period in which the men participated in daily hot-water baths showed a reduction of fasting blood sugar and insulin levels as well as improved low-grade inflammation at rest.

While previous studies have already established a link between obesity and depression, in a study that claims to have found the strongest evidence regarding the link between the two, researchers have found that obesity causes depression, even in the absence of other health problems.

The research was published in the International Journal of Epidemiology.

“The team looked at UK Biobank data from more than 48,000 people with depression and compared them to more than 290,000 controls in the UK Biobank cohort of people born between 1938 and 1971, who have provided medical and genetic information. They used hospital admission data and self-reporting to determine whether people had depression”, University of Exeter’s website mentions.

The team separated the psychological component of obesity from the impact of obesity-related health problems using genes associated with higher BMI but lower risk of diseases like diabetes. In an interesting turn of events, it was found that these genes were just as strongly associated with depression as those genes associated with higher BMI and diabetes, which suggests that a higher BMI causes depression both with and without related health issues.

It was found that this effect was stronger in women than in men. “At the other ends of the BMI spectrum, very thin men are more prone to depression than men of normal weight and very thin women”, the study mentioned.

According to Professor Hypponen, Director of the Australian Centre for Precision Health, who co-led the study, “Our research shows that being overweight doesn’t just increase the risks of chronic diseases such as cancer and cardiovascular disease; it can also lead to depression”.