Nutritional Support: Backed by Science

Innovation and technology
Weight loss
Accompagnement nutritionnel : science à l’appui

The new Canadian guidelines for adult obesity management recommend individualized nutritional therapy provided by a registered dietitian-nutritionist for weight loss, improved quality of life, and reduced risk of cardiovascular disease (1). Similar recommendations are echoed in the latest American guidelines for pediatric obesity management, emphasizing high and regular frequency for favourable outcomes (2). Here is a summary of the literature on the importance of long-term nutritional support.

Weight Management in Adults

A systematic review published in 2023, encompassing 73 studies, including 62 randomized controlled trials, demonstrated that interventions led by nutritionists, involving at least 5 sessions over a minimum period of 12 months, led to significant and more favourable improvements in weight loss, waist circumference, cardiometabolic factors, and quality of life in adults with overweight or obesity compared to shorter interventions (3). Interestingly, in-person and hybrid modes of sessions showed more significant effects than exclusively virtual meetings (telehealth) for several cardiometabolic parameters, including BMI reduction, waist circumference, blood pressure, and fasting glucose (3). These results highlight the effectiveness of interventions led by nutritionists and suggest that duration, frequency, and mode of support can influence outcomes.

And for Children and Adolescents?

When it comes to weight management interventions for overweight or obese children and adolescents, the duration of nutritional support plays a crucial role. Interventions focusing on lifestyle habits exceeding 26 hours of contact show notable effectiveness in maintaining or reducing weight after 6 to 12 months of intervention (4). The results also indicate a dose-response relationship for BMI reduction and cardiometabolic measures, with improvements in blood pressure observed in interventions offering ≥52 hours of contact (4). No statistically significant improvement was observed for lipid profiles, although some improvements were noted for insulin and glucose measures. The effectiveness of interventions is strongly linked to the estimated number of contact hours, emphasizing the importance of intensity for positive outcomes (4). Additionally, no adverse effects were reported in children and adolescents, such as eating disorders or body dissatisfaction, highlighting the safety of these interventions (4).

Impact on Cardiometabolic Measures

Two other studies also underscore the importance of nutritional support with a nutritionist alone or as part of an interdisciplinary team for managing cardiometabolic factors, showing significant improvements in glycemia in adults with type 2 diabetes (5) and blood pressure (5,6). A randomized controlled trial involving 187 adults aimed to measure changes in 24-hour systolic blood pressure after 12 weeks of fully remote interventions. The intervention, facilitated through mobile applications, consisted of recommendations from the American Heart Association on a healthy diet and participation in 180 minutes or more of physical activity per week, with or without additional support from a nutritionist in the form of weekly motivational phone interviews (6). Both approaches using mobile applications (with or without additional nutritionist support) resulted in similar clinically significant reductions in 24-hour systolic blood pressure of -4,92 to -6,73 mm Hg (6). The group receiving additional support from a nutritionist also saw improvements in blood pressure during sleep and a greater increase in physical activity (6). Weekly nutritional support with digital therapy is beneficial for optimizing cardiometabolic health.

Maintaining Habits Long Term

Two key studies shed light on effective strategies for long-term weight and habit maintenance. The first systematic review and meta-analysis based on 27 clinical studies involving 7,236 adults with a BMI over 30 kg/m2 indicated that lifestyle change interventions of 12 weeks or more remain effective for achieving clinically significant weight loss (at least 5% of initial body weight), ranging between 4.88 kg to 28 kg. Weight regain typically began around 36 weeks after the end of the initial intervention period. At 48 weeks of follow-up, some participants had regained all lost weight, while others maintained clinically significant weight loss up to 160 weeks after the end of the intervention. The pooled analysis, including five different studies at 160 weeks post-intervention, showed an average weight loss of 5.3% (7). The results of their meta-analysis demonstrated that dietary interventions, alone or in combination with exercise, with an intervention duration of 12 weeks (no notable benefit from longer interventions), accompanied by a nutritionist (alone or as part of a small team of healthcare professionals) during both the weight loss and maintenance phases with contact at least once a month, had the most favourable long-term results (7).


Another systematic review, based on 21 articles involving 62,565 adults, evaluated participants' ability to make changes to their diet, such as reducing fat intake and increasing fruit and vegetable consumption and dietary fibre, and maintaining these changes for at least 12 months (8). According to the results, studies providing more intense and frequent support to participants favour the maintenance of dietary changes (8). Notably, the most successful study required intensive intervention of 69 contacts over four years, including 19 individual sessions with a nutritionist, 14 group sessions, and 36 regular phone calls (9). These studies show that frequent support is the key to maintaining eating habits over the long term.

Key Takeaways

Interventions based on dietary habit changes, including those focused on weight loss, with intensive contact, show promising results, especially in adults, adolescents, and children. The relationship between contact hours and the size of the effect underscores the importance of a personalized and regular approach in supporting both behavioural change as well as maintenance of the new behaviour. It is crucial to recognize that time invested into these interventions is key for sustainable results. Consult a TeamNutrition nutritionist for optimal support and long-term success for your patients-clients.


  1. Brown J, Clarke C, Johnson Stoklossa C, Sievenpiper J. Canadian Adult Obesity Clinical Practice Guidelines: Medical Nutrition Therapy in Obesity Management. Available from: Accessed [January 2024]. 
  2. Hampl, S. E., Hassink, S. G., Skinner, A. C., Armstrong, S. C., Barlow, S. E., Bolling, C. F., ... & Okechukwu, K. (2023). Clinical practice guideline for the evaluation and treatment of children and adolescents with obesity. Pediatrics, 151(2), e2022060640.
  3. Morgan-Bathke, M., Baxter, S. D., Halliday, T. M., Lynch, A., Malik, N., Raynor, H. A., ... & Rozga, M. (2022). Weight Management Interventions Provided by a Dietitian for Adults with Overweight or Obesity: An Evidence Analysis Center Systematic Review and Meta-Analysis. Journal of the Academy of Nutrition and Dietetics.
  4. O’Connor, E. A., Evans, C. V., Burda, B. U., Walsh, E. S., Eder, M., & Lozano, P. (2017). Screening for obesity and intervention for weight management in children and adolescents: evidence report and systematic review for the US Preventive Services Task Force. JAMA, 317(23), 2427-2444.
  5. Razaz, J. M., Rahmani, J., Varkaneh, H. K., Thompson, J., Clark, C., & Abdulazeem, H. M. (2019). The health effects of medical nutrition therapy by dietitians in patients with diabetes: A systematic review and meta-analysis: Nutrition therapy and diabetes. Primary care diabetes, 13(5), 399-408.
  6. Chang, A. R., Gummo, L., Yule, C., Bonaparte, H., Collins, C., Naylor, A., ... & Bailey‐Davis, L. (2022). Effects of a Dietitian‐Led, Telehealth Lifestyle Intervention on Blood Pressure: Results of a Randomized, Controlled Trial. Journal of the American Heart Association, 11(19), e027213.
  7. Machado, A. M., Guimarães, N. S., Bocardi, V. B., da Silva, T. P. R., do Carmo, A. S., de Menezes, M. C., & Duarte, C. K. (2022). Understanding weight regain after a nutritional weight loss intervention: Systematic review and meta-analysis. Clinical nutrition ESPEN, 49, 138-153.
  8. Chapman, K. (2010). Can people make healthy changes to their diet and maintain them in the long term? A review of the evidence. Appetite, 54(3), 433-441.
  9. Lanza, E., Schtzkin, A., Daston, C., Corle, D., Freedman, L., Ballard-Barbash, R., et al. (2001). Implementation of a 4-y, high-fiber, high-fruit-and-vegetable, low-fat dietary intervention: results of dietary changes in the Polyp Prevention Trial. American Journal of Clinical Nutrition, 74, 387–401.
Registered Dietitian Nutritionist