Weight Loss Trials

January 2023

January is typically when consumers redouble their efforts to lose weight and improve eating habits. It can be hard to lose weight, due to the strong physiological drive to increase food consumption and conserve energy during periods of negative energy balance. Weight loss programs that optimize nutritional quality while minimizing feelings of hunger are most likely to be successful.

When searching for a weight loss program, consumers are more likely to select a diet plan that has been shown to be effective and which will work best for them and their habits.

Demonstrating the effectiveness of a diet plan in a way that resonates with consumers is therefore a significant priority for companies. There are several types of clinical trials that provide claims support and demonstrate the effectiveness of weight loss plans:

Long term weight loss

Long term weight loss trials are the gold standard of weight loss trials. Their duration can range anywhere from one month to over one year. Participants record their adherence to the diet plan and attend study visits to assess their compliance, as well as to provide samples and have measurements taken, depending on the study’s objectives. Some weight loss trials compare different weight loss plans to each other, while others assess the effectiveness of only one plan. Some trials incorporate a maintenance phase to demonstrate that the weight lost during the trial can be maintained, which will provide further support for the long term effectiveness claim of the diet plan.

Changes in body composition

Change in body composition, such as percent body fat and muscle mass, can be a primary or secondary endpoint. This is assessed during study visits through clinical measurements.

Appetite and satiety

Acute trials can be useful in assessing subjective and/or objective feelings of satiety and hunger following the consumption of specific foods. These trials demonstrate the effectiveness of food products to promote satiety and therefore improve adherence to and satisfaction with the diet plan.

Feelings of wellness

Feelings of wellness are a significant component in weight loss plans, since this is an important priority for people looking to make changes to their lives and routines. It also contributes to adherence. These measures are often included in weight loss trials.


Consumer enjoyment of the study product matters! Liking can contribute to feelings of fullness as well as adherence and can be included in a robust study design.