Healthy Diets Yield Cardiometabolic Improvements Independent of Weight Loss

Recent research conducted by experts at the Harvard T.H. Chan School of Public Health and Ben Gurion University in Israel indicates that adopting a nutritious diet can lead to significant cardiometabolic benefits, regardless of weight loss. The study reveals that nearly one-third of participants who committed to a healthy eating plan did not experience any change in weight, yet still enjoyed various health advantages.

The findings highlight notable improvements in crucial cardiometabolic markers among participants, including elevated levels of high-density lipoprotein (HDL) cholesterol--often referred to as 'good' cholesterol--decreased leptin levels (the hormone that signals hunger), and reduced amounts of visceral fat, which is deep abdominal fat that can surround vital organs.

Lead researcher Anat Yaskolka Meir emphasized that societal norms often equate health with weight loss. She noted that individuals who do not lose weight are frequently regarded as unsuccessful. Meir's research offers a different perspective, suggesting that metabolic health can improve even without weight loss, which she considers a hopeful message rather than one of failure.

Published in the European Journal of Preventive Cardiology, the study analyzed data from 761 individuals with abdominal obesity who were part of three significant workplace nutrition trials: DIRECT, CENTRAL, and DIRECT-PLUS. Participants adhered to various healthy diets--including low-fat, low-carbohydrate, Mediterranean, and green-Mediterranean diets--for periods ranging from 18 to 24 months.

The results showed that 36% of participants achieved clinically significant weight loss, defined as more than a 5% reduction from their initial body weight, while another 36% experienced moderate weight loss of up to 5%. Approximately 28% of participants were resistant to weight change, either maintaining their weight or gaining some. Notably, the study found that weight loss correlated with multiple health improvements. Each kilogram lost was associated with a 1.44% increase in HDL cholesterol, a 1.37% decrease in triglycerides, a 2.46% reduction in insulin levels, a 2.79% drop in leptin, and a 0.49-unit decrease in liver fat, along with lower blood pressure and liver enzyme levels.

Interestingly, participants who did not experience significant weight changes--often older individuals or women--also demonstrated many of the same health benefits. They showed improvements in HDL cholesterol, lower leptin levels, and a reduction in harmful visceral fat. Meir remarked on the significant metabolic shifts that occurred within these individuals, indicating that a healthy diet can be effective even when weight remains constant.

Utilizing advanced omics tools, the researchers identified 12 specific DNA methylation sites that might predict long-term weight loss responses. Corresponding author Iris Shai noted that this groundbreaking discovery suggests that certain individuals may have a biological predisposition to respond differently to dietary interventions, indicating that factors beyond willpower and discipline are at play in weight management.

The study does highlight some limitations, particularly the predominance of male participants. The researchers recommend that future investigations should aim to include a more balanced gender representation to further understand these dynamics.

For further details, refer to the study published in the European Journal of Preventive Cardiology.