Study: Successful weight loss depends on more protein and fiber while restricting calories

(A) Percent weight loss over the course of a year. Participants are grouped by weight loss of >5% (n = 9) and Obesity Science & Practice (2024). DOI: 10.1002/osp4.764

Participants in a self-directed nutrition education program who had the greatest success losing weight over a 25-month period consumed more protein and fiber, according to one study. Personalization and flexibility were also key in creating plans that dieters could stick to over time.

After one year, successful dieters (41% of participants) had lost 12.9% of their body weight, compared to the rest of the sample studied, who lost just over 2% of their starting weight, according to an article about the study published in. Science and practice of obesity.

The dieters participated in the Individualized Diet Improvement Program, which uses data visualization tools and intensive nutrition education to increase dieters’ knowledge of key nutrients, giving them the ability to create a personalized, safe and effective weight-loss plan, says Manabu T. Nakamura, a professor of nutrition at the University of Illinois Urbana-Champaign and leader of the study.

“Flexibility and personalization are key in developing programs that optimize dieters’ success in losing and maintaining weight,” said Nakamura. “Maintaining a healthy weight requires achieving sustainable dietary change, which varies from person to person. The iDip approach allows participants to experiment with different dietary variations, and the knowledge and skills they develop while losing weight serve as a foundation for sustainable weight maintenance.”

The pillars of iDip are increased protein and fiber intake and a daily intake of 1,500 calories or less.

Based on the Institutes of Medicine’s dietary guidelines, the iDip team developed a unique, two-dimensional quantitative data visualization tool that plots the protein and fiber density of foods per calorie and provides a target range for each meal. Starting with foods they normally ate, dieters created an individualized plan where they increased their protein intake to about 80 grams and their fiber intake to about 20 grams daily.

By tracking participants’ eating habits and weight using Wi-Fi-enabled scales, the team found that there was a strong inverse relationship between the percentage of fiber and protein consumed and the dieters’ weight loss.

“The research strongly suggests that increasing protein and fiber intake while reducing calories is needed to optimize the safety and effectiveness of weight loss diets,” said lead author and University of Illinois graduate Mindy H. Lee, a then-doctoral student and registered dietitian for the iDip program.

Nakamura said that maintaining muscle mass is very important when losing weight, especially when taking weight loss medications.

“Recently, the popularity of injectable weight loss drugs has increased”said Nakamura. “However, taking these medications while severely restricting food intake can cause serious side effects such as muscle and bone loss unless protein intake is increased during weight loss.”

A total of 22 people who participated in the program completed it, including nine men and 13 women. Most of the dieters were between 30 and 64 years old. Participants reported that they had already made two or more attempts to lose weight. They also suffered from various comorbidities – 54% had high cholesterol, 50% had skeletal problems and 36% suffered from high blood pressure and/or sleep apnea. In addition, the dieters reported diagnoses of diabetes, non-alcoholic fatty liver disease, cancer and depression, according to the study.

The seven dieters who reported being diagnosed with depression lost significantly less weight – about 2.4% of their baseline weight compared to those without depression, who lost 8.39% of their baseline weight. The team found that weight loss did not differ significantly among participants with other comorbidities, or between younger and older participants, or between men and women.

Body composition analysis showed that dieters maintained their lean body mass and lost an average of 7.1 kilograms of fat mass and only minimal muscle mass over the 6-month interval. Among those who lost more than 5% of their starting weight, 78% of the weight lost was fat, according to the study.

Overall, participants reduced their fat mass from an average of 42.6 kilograms at the start of the program to 35.7 kilograms after 15 months. Likewise, dieters reduced their waist circumference by about 7 centimeters after six months and by a total of 9 centimeters after 15 months, the team found.

By monitoring protein and fiber intake of dieters, the team found that there was a strong association between protein and fiber consumption and weight loss after three and twelve months.

“The strong correlation suggests that participants who were able to make sustainable dietary changes within the first three months continued to lose weight in the following months, while those who initially had difficulty implementing sustainable dietary patterns were barely able to change their diet in the later months,” Nakamura said.

The team hypothesized that this association might also be related to the early weight loss successes of some dieters, which may have increased their motivation and persistence with their program.