Study design and methodology

The Metabolic Basis of Human Adipose Tissue in Health and Disease Research Laboratory specializes in carrying out complex clinical studies with human volunteers. These studies help us better understand the physiology, structure and metabolism of fat tissue, including in people who have gained extra body fat.

Reflecting our commitment to building knowledge and improving patient care through team-based, collaborative science, this page provides details about our study designs and methodologies that may be useful for other metabolic health and disease researchers.

Criteria and compensation

Some of our studies have body weight criteria for participation. In some cases, we use body mass index (BMI) — a combination of height and weight to estimate body fat — to determine whether participants meet these criteria. We calculate participant BMI using Mayo Clinic's BMI and waist circumference calculator.

Some studies require overnight stays at Mayo Clinic Hospital — Rochester, Saint Marys Campus, as well as biopsies, IVs and other invasive procedures.

We do not expect volunteers to participate in our studies for free. Volunteers may be paid between $400 and $2,000 for completion of a study.

Treatment studies

Why weight loss causes different kinds of fat loss

Clinical trial 24-011351: Mechanisms of Regional Fat Loss in Humans

The body treats fat tissue differently in the legs versus in the abdomen. This may help explain why some people gain and lose more fat in the abdomen, while others gain and lose more fat in the legs. We do not yet know why this happens, but it may be related to how leg fat and abdominal fat respond to changes in diet.

In this study, we are trying to understand how leg fat and abdominal fat respond to a 12-week controlled weight-loss diet. To answer this question, we measure fat tissue function before and after the diet.

We collect or measure the following:

  • Blood samples.
  • Fat samples taken via miniature liposuction.
  • Adipose tissue blood flow.
  • Metabolic rate.

Volunteers agree to have small probes placed into their leg fat and abdominal fat. They lie in bed for five hours while we collect blood and breath samples to understand how fat tissue responds.

Volunteers spend two nights and two days in the Clinical Research and Trials Unit at Mayo Clinic Hospital — Rochester, Saint Marys Campus, before the 12-week diet and two more nights and days after the diet. They also receive many of their meals from the Clinical Research and Trials Unit kitchen to consume at home throughout the diet. This helps ensure that meals have the correct number of calories to promote weight loss. These meals also provide inspiration on how participants can cook with fewer calories at home.

Volunteers are compensated up to $2,000 for finishing the study.

Studies on environmental effects on adipose tissue

Circadian effects: How the day-night cycle affects fat tissue

Clinical trial 20-004280: A Study to Evaluate Circadian Regulation of Human Adipose Tissue Metabolism

Fat tissue behaves very differently during the day than it does at night. This is probably because of how people eat. People eat mostly during the day, forcing fat cells to respond to the meals, and people fast at night. But it also is possible that fat tissue responds to the day-night cycle independently of food intake.

In this study, we are trying to understand whether both of these factors affect how fat tissue behaves. We also want to know whether people who have gained extra body fat are particularly affected by the day-night cycle.

To answer these questions, we are studying the effects of three meals a day vs. continuous feeding, day and night. Study participants agree to have a small, flexible tube placed through the nose into the stomach. They receive liquid food either as a constant infusion or as three liquid meals a day. We collect fat samples via miniature liposuction as well as blood samples to understand fat tissue response.

Volunteers spend two nights and one full day in the Clinical Research and Trials Unit at Mayo Clinic Hospital — Rochester, Saint Marys Campus. Volunteers are compensated up to $1,000 for completion of the study.

Exosome effects: Does fat tissue release particles into the blood after meals?

Clinical trial 24-007465: A Study of Upper Body Subcutaneous Adipose Tissue

This study is designed to understand whether exosomes — small cellular particles that carry cargo to communicate between cells or between tissues — are altered after a meal, and whether there are differences in how they are altered in people with different amounts of body fat.

We collect fat samples via miniature liposuction as well as blood samples. These samples help us understand how fat tissue responds to the food intake.

Volunteers have two brief outpatient visits in the Clinical Research and Trials Unit at Mayo Clinic Hospital — Rochester, Saint Marys Campus. Volunteers are compensated up to $350 for completion of the study.

Physiological effects: Does blood flow to fat tissue go down as people age?

Clinical trial 23-004200: Adipose Tissue Blood Flow of Older Adults

Fat tissue, like many other tissues, changes as part of the aging process. One of the possible age-related changes that can affect how well fat tissue functions is blood flow.

In this study, we measure blood flow to fat tissue on two occasions: once in response to drinking sugar water and once after eating a meal. We compare these responses in older adults and younger adults.

We also collect fat biopsies via miniature liposuction. These samples help us understand whether differences in blood flow affect fat cells.

Volunteers spend two half days in the Clinical Research and Trials Unit at Mayo Clinic Hospital — Rochester, Saint Marys Campus. Volunteers are compensated up to $550 for completion of the study.

Studies on hormonal control of adipose tissue

Body fat response to adrenaline, insulin and niacin: Multiple studies

The body treats fat tissue differently in the legs versus in the abdomen. This may help explain why some people gain more fat in the abdomen, while others gain more fat in the legs. We do not yet know why this happens, but it may be related to how fat cells in different parts of the body respond to substances such as:

  • Adrenaline.
  • Insulin.
  • Niacin.

In three separate studies, we are trying to understand how each substance affects leg fat and abdominal fat in people with different amounts of body fat. To explore this question, we collect blood samples from vessels in the leg and fat samples via miniature liposuction. We collect these samples before and during administration of an IV containing the substance we are testing.

People who volunteer for any of these studies agree to have small tubes called catheters placed in the two main blood vessels in the groin area. During the study, the volunteers lie in bed while we collect blood and fat samples. The samples help us understand how fat tissue responds to the substance in question. The adrenaline and niacin studies take five hours. The insulin study takes seven hours.

Volunteers spend one night and one full day in the Clinical Research and Trials Unit at Mayo Clinic Hospital — Rochester, Saint Marys Campus. Volunteers are compensated up to $1,000 for completing any one of the studies.

View details for each study: