The Science Behind Sustainable Weight Loss and Weight Maintenance

By Hugo Francisco de SouzaReviewed by Benedette Cuffari, M.Sc.

Introduction
Why January spikes interest in weight loss
Short-term strategies with strong evidence
Physical activity foundations
Dietary patterns with evidence
Effective behavioral changes
When medication or clinician input is appropriate
References
Further reading

Evidence shows that weight management outcomes are shaped not only by diet and exercise but also by timing, adherence, and clinical support. Initiating structured interventions early in the year aligns behavioral momentum with metabolic and medical strategies to improve long-term weight loss and disease risk reduction.

Introduction

Effective weight management depends on the interaction of timing, biology, and psychology. This article reviews evidence-based approaches, including precise protein leveraging, GLP-1 mimicking dietary strategies, and pharmacological treatments, that can promote long-term weight loss goals.

Psychological research increasingly suggests that the start of a new year allows individuals to separate past failures from their sense of a renewed self. While public skepticism questions the longevity of these resolutions, recent large-scale data indicate a distinct clinical advantage for those who initiate care in January.¹

Image Credit: Nanci Santos Iglesias / Shutterstock.com

Why January spikes interest in weight loss

A prospective cohort study from the National Health Service (NHS) Diabetes Prevention Program analyzed data from 85,514 participants and found that the month of initiation was a significant predictor of success. Specifically, those who began their weight management program in January achieved 12 % to 30 % greater weight loss compared to those starting at other times of the year.¹

January starters lost significantly more weight than those starting in November or March, suggesting that the collective social momentum of the New Year enhances program attendance and adherence, which are critical mediators of weight loss.¹

Short-term strategies with strong evidence

Calorie awareness and energy balance

Current public health guidelines recommend a daily energy deficit of 500–750 kcal to achieve sustainable weight loss of 0.5–0.7 kg every week. However, the accuracy of monitoring this deficit is often compromised by measurement error.²

For example, a 2022 study revealed significant underreporting of energy intake across all body mass index (BMI) categories, particularly among individuals with higher activity levels and of a younger age. When energy intake was allometrically scaled to total energy expenditure, obese and nonobese adults demonstrated comparable levels of misreporting.²

High-protein dietary structure

Although managing calorific intake is essential, macronutrient composition dictates the quality of weight loss. In fact, the preservation of lean body mass (LBM) is widely recognized as crucial for maintaining an optimal resting metabolic rate.⁴

A 2024 network meta-analysis of 78 randomized controlled trials (RCTs) confirmed that protein intake exceeding the standard allowance is protective for maintaining weight loss. Higher protein intake significantly reduced lean mass loss during energy restriction, particularly when combined with resistance training.⁴

Physical activity foundations

Modifiable behaviors like diet, physical activity levels, and sleep patterns are essential for managing weight loss. Nevertheless, recent research demonstrates that physical activity is often less effective than dietary restriction for achieving acute weight loss; however, it remains essential for long-term weight maintenance.⁵

Recent reviews emphasize the role of non-exercise activity thermogenesis (NEAT) and non-exercise physical activity (NEPA). A meta-analysis found no clinically meaningful average change in NEPA during structured exercise interventions, although compensatory reductions may occur in specific populations.⁵

Video credit: MayoClinic/Youtube.com

Dietary patterns with evidence

Modern nutritional science increasingly recommends prioritizing dietary patterns that optimize metabolic health rather than focusing on single-nutrient exclusion. The Mediterranean, DASH, and high-protein dietary patterns are commonly promoted for achieving caloric reduction while preserving cardiometabolic health.⁶

Mediterranean, DASH, and high-protein patterns

A 2025 network meta-analysis demonstrated that although multiple diets produce weight loss, they differ meaningfully in cardiometabolic outcomes.⁶

The ketogenic diet was associated with the greatest diastolic blood pressure reduction, followed by DASH and Mediterranean diets. The Mediterranean diet showed comparatively modest weight loss but superior glycemic regulation and long-term adherence.⁶

Approaches to activate GLP-1

Meal sequencing and viscous dietary fibers are being increasingly studied for their role in appetite regulation. A 2023 randomized controlled trial found that consuming protein and vegetables before carbohydrates resulted in modest but significant weight loss in adults with prediabetes, primarily through improved dietary quality rather than glycemic changes.⁷

Preclinical evidence indicates that highly soluble beta-glucan fibers inhibit alpha-glucosidase activity and promote microbial production of short-chain fatty acids, which act on intestinal L-cells to stimulate endogenous GLP-1 secretion.⁸

Effective behavioral changes

Behavioral tools such as habit stacking, anchoring new behaviors to existing routines, can support sustained weight loss. A 2024 systematic review reported median habit formation times of 59–66 days, with implementation intentions (e.g., if/then planning) significantly improving habit automaticity during early behavior change phases.⁹

When medication or clinician input is appropriate

BMI and waist circumference thresholds

BMI remains the most widely used screening tool for overweight and obesity. However, waist circumference (WC) is increasingly recognized as a superior marker of visceral adiposity and cancer risk.

A 2025 UK Biobank analysis of 315,457 adults demonstrated that exceeding the WHO-recommended waist circumference thresholds was associated with an 11 % higher risk of total cancer, even among individuals meeting physical activity guidelines. Conversely, sufficient physical activity attenuated, but did not eliminate, the cancer risk associated with abdominal obesity, highlighting WC as an independent risk factor rather than a surrogate of inactivity.¹⁰

Criteria for GLP-1 agonists

The 2025 American College of Cardiology (ACC) Expert Consensus Statement recommends that anti-obesity pharmacotherapy such as semaglutide or tirzepatide may be considered first-line therapy for eligible patients rather than reserved for post-lifestyle failure.¹¹ Eligibility is defined as a BMI ≥30 kg/m² or ≥27 kg/m² with obesity-related complications.

Patients should not be required to ‘try and fail’ lifestyle changes prior to initiating pharmacotherapy.¹¹

References

1. Koutoukidis, D. A., Barron, E., Stevens, R., Aveyard, P., Valabhji, J., & Jebb, S. A. (2023). Association between the month of starting a weight management program and weight change in people at high risk of type 2 diabetes: A prospective cohort study. Obesity, 31(6), 1707–1716. DOI:10.1002/oby.23762, https://onlinelibrary.wiley.com/doi/10.1002/oby.23762
2. Waterworth, S. P., Kerr, C. J., McManus, C. J., Costello, R., & Sandercock, G. R. H. (2022). Obese individuals do not underreport dietary intake to a greater extent than nonobese individuals when data are allometrically‐scaled. American Journal of Human Biology, 34(7). DOI:10.1002/ajhb.23743, https://onlinelibrary.wiley.com/doi/10.1002/ajhb.23743
3. Spreckley, M., Seidell, J., & Halberstadt, J. (2021). Perspectives into the experience of successful, substantial long-term weight-loss maintenance: a systematic review. International Journal of Qualitative Studies on Health and Well-Being, 16(1). DOI:10.1080/17482631.2020.1862481, https://www.tandfonline.com/doi/full/10.1080/17482631.2020.1862481
4. Liao, C.-D., Huang, S.-W., Chen, H.-C., Huang, M.-H., Liou, T.-H., & Lin, C.-L. (2024). Comparative Efficacy of Different Protein Supplements on Muscle Mass, Strength, and Physical Indices of Sarcopenia among Community-Dwelling, Hospitalized or Institutionalized Older Adults Undergoing Resistance Training: A Network Meta-Analysis of Randomized Controlled Trials. Nutrients, 16(7), 941. DOI:10.3390/nu16070941, https://www.mdpi.com/2072-6643/16/7/941
5. Fedewa, M. V., Hathaway, E. D., Williams, T. D., & Schmidt, M. D. (2016). Effect of Exercise Training on Non-Exercise Physical Activity: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Sports Medicine, 47(6), 1171–1182. DOI:10.1007/s40279-016-0649-z, https://link.springer.com/article/10.1007/s40279-016-0649-z
6. Lv, J., Jiao, S., Li, W., Ding, S., Ma, L., & Zhang, Q. (2025). Network meta-analysis of the effects of different dietary patterns on patients with metabolic syndrome. Frontiers in Nutrition, 12. DOI:10.3389/fnut.2025.1634545, https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1634545/full
7. Shukla, A. P., et al. (2023). A Randomized Controlled Pilot Study of the Food Order Behavioral Intervention in Prediabetes. Nutrients, 15(20), 4452. DOI:10.3390/nu15204452, https://www.mdpi.com/2072-6643/15/20/4452
8. Marcobal, A. M., et al. (2024). Highly Soluble β-Glucan Fiber Modulates Mechanisms of Blood Glucose Regulation and Intestinal Permeability. Nutrients, 16(14), 2240. DOI:10.3390/nu16142240, https://www.mdpi.com/2072-6643/16/14/2240
9. Singh, B., Murphy, A., Maher, C., & Smith, A. E. (2024). Time to Form a Habit: A Systematic Review and Meta-Analysis of Health Behaviour Habit Formation and Its Determinants. Healthcare, 12(23), 2488. DOI:10.3390/healthcare12232488, https://www.mdpi.com/2227-9032/12/23/2488
10. Bohmann, P., et al. (2025). WHO guidelines on waist circumference and physical activity and their joint association with cancer risk. British Journal of Sports Medicine, 59(6), 360–366. DOI:10.1136/bjsports-2024-108708, https://bjsm.bmj.com/content/59/6/360
11. Gilbert, O., Gulati, M., & Gluckman, T. J. (2025). 2025 Concise Clinical Guidance: An ACC Expert Consensus Statement on Medical Weight Management for Optimization of Cardiovascular Health. Journal of the American College of Cardiology. DOI:10.1016/j.jacc.2025.05.024, https://www.jacc.org/doi/10.1016/j.jacc.2025.05.024. Accessed 18 December 2025.

Further Reading

• All Weight Loss Content
• What to Look for in a Protein Powder?
• Mental Health Disorders, Weight Gain, and Exercise
• Circadian Rhythm and Weight Loss
• Wegovy: A Breakthrough in Weight Loss?

Last Updated: Jan 9, 2026