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Very Low Calorie Diets: An Evidence-Based Approach

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The 2001 Look AHEAD (Action for Health in Diabetes) trial was groundbreaking for its findings related to weight loss and maintenance through intensive lifestyle intervention, including the use of a Very Low Calorie Diet (VLCD). The purpose of the study was to identify the influence of weight loss on cardiovascular morbidity and mortality in people with obesity that had type 2 diabetes. The outcomes of this trial have served as a foundation for continued research on the efficacy and safety of VLCDs over the past 20 years. In this post we will review some of the foundational and more current (within five years) research supporting the use of VLCDs across populations and the medical continuum of care.

The data collected over the eight year span of the Look AHEAD trial provided invaluable information about medical and quality of life outcomes. Improvements to lipids, blood pressure and glucose management were found, as well as positive outcomes for renal disease, sleep apnea and depression. Importantly, weight loss was significantly higher for the intervention participants, regain was slower and maintenance of loss was higher.

The Diabetes Remission Clinical Trial (DiRECT), which also used total meal replacements, began in 2014 to determine if a weight loss of at least 15kg would lead to diabetic remission without medication for at least two months. The goal was achieved, and 46 percent of the intervention group experienced remission at 12 months, with 36 percent still in remission at 24 months. Additionally, the intervention group experienced significant reduction in systolic and diastolic blood pressure and improvement in triglyceride levels, used fewer medications and reported a significant improvement to quality of life.

These studies spurred further investigations and current research continues to support the benefits of weight loss using a VLCD. Several studies confirm that the reduction or elimination of insulin treatment or other diabetes medications is possible when patients follow a VLCD (e.g., Fatati, 2020; Pareja, etal., 2020). Evert and others (2019) also support the use of VLCD as an option for nutrition therapy as a means of quality diabetes care.

Positive outcomes extend beyond the diabetic population to include those with cardiovascular, nephrological, orthopedic and other issues. Among geriatric populations, for example, VLCDs led to greater weight loss and reduction in waist circumference, fat mass and android fat. There were also significant improvement ins HbA1c and improvements in multiple cardiovascular risk markers (Haywood, etal., 2017 and 2019).

Further, VLCDs have been used safely by patients with kidney disease when medically supervised (Woods, etal., 2019), and led to metabolic and clinical changes in patients with non-alcoholic fatty liver disease (Schwenger, Fischer, Jackson, Okrainec & Allard, 2018). Rehackova and colleagues’ 2017 study took a different approach and looked at patients’ experiences when using meal replacements. Patients indicated that although it required effort, adherence to a VLCD for eight weeks was easier than expected and was perceived as “highly gratifying.”

While there is no “one-size-fits-all” approach to weight loss, these and other clinical trials and secondary reviews suggest that VLCDs are comparable or more effective than other weight loss methods, not only in the amount of weight loss but also in terms of physical and mental health improvements. Benefits have been shown both for short-term (≤ 12 months) and longer term (≥ 12 months) outcomes when used as part of a medically supervised program. To ensure the most effective options are available to those who need them, the medical community should consider all weight loss options for treating patients with obesity and their comorbid diseases, and include VLCDs among their recommendations as part of a lifestyle change.

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