New Study Reveals Protein and Fiber as Key to Successful Weight Loss

A new study from the University of Illinois highlights the crucial role of higher protein and fiber consumption in successful weight loss. Personalized and flexible diet plans helped participants lose an average of 12.9% of their body weight over a year.

A groundbreaking new study from the University of Illinois reveals that participants following a self-directed dietary education program, which emphasized higher protein and fiber intake while limiting calories, achieved significant weight-loss success over 25 months. Personalization and flexibility in diet plans emerged as vital factors in helping dieters adhere to their plans and achieve sustainable results.

At the one-year mark, the study, published in Obesity Science and Practice, found that 41% of participants managed to lose an average of 12.9% of their body weight. In contrast, the rest of the sample lost only about 2% of their initial weight.

The research was part of the Individualized Diet Improvement Program (iDip), which utilizes data visualization tools and extensive dietary education sessions. This approach empowered participants to design personalized, safe and effective weight-loss strategies.

“Flexibility and personalization are key in creating programs that optimize dieters’ success at losing weight and keeping it off,” Manabu T. Nakamura, professor of nutrition at the University of Illinois Urbana-Champaign and the study’s lead researcher, said in a news release. “Sustainable dietary change, which varies from person to person, must be achieved to maintain a healthy weight. The iDip approach allows participants to experiment with various dietary iterations, and the knowledge and skills they develop while losing weight serve as the foundation for sustainable maintenance.”

Key components of the iDip included increasing daily protein intake to approximately 80 grams and fiber intake to about 20 grams, along with consuming no more than 1,500 calories daily. The study found strong inverse correlations between higher protein and fiber consumption and participants’ weight loss.

“The research strongly suggests that increasing protein and fiber intake while simultaneously reducing calories is required to optimize the safety and efficacy of weight loss diets,” first author and University of Illinois alumna Mindy H. Lee, who was a graduate student and registered dietitian-nutritionist for the iDip program at the time of the research, said in the news release.

Nakamura also noted the importance of preserving lean mass during weight loss, especially with the rising popularity of weight-loss medications.

“Using these medications when food intake is strongly limited will cause serious side effects of muscle and bone loss unless protein intake is increased during weight loss,” he said.

Out of the 22 participants who completed the program, nine were men and 13 were women, most aged between 30 and 64. Many had attempted to lose weight multiple times before and had various health conditions, including high cholesterol, skeletal problems, hypertension, diabetes and depression.

Interestingly, those with depression lost significantly less weight — about 2.4% of their starting weight — compared to participants without depression, who lost approximately 8.39%. However, weight loss did not significantly differ among those with other comorbidities or across different age and gender groups.

Participants who successfully adhered to the dietary changes maintained their lean body mass, shedding an average of 7.1 kilograms of fat while losing minimal muscle mass over six months. Moreover, those who lost more than 5% of their starting weight saw 78% of this loss come from fat.

By 15 months, participants reduced their fat mass from 42.6 kilograms to 35.7 kilograms and diminished their waist measurements by about 9 centimeters.

The study established a strong correlation between sustained early dietary changes and continued weight loss success.

“The strong correlation suggests that participants who were able to develop sustainable dietary changes within the first three months kept losing weight in the subsequent months, whereas those who had difficulty implementing sustainable dietary patterns early on rarely succeeded in changing their diet in the later months,” Nakamura added.