Office of Research & Development
Overweight and obesity are terms used for ranges of weight that are greater than what is considered healthy. According to the U.S. Centers for Disease Control and Prevention, nearly 35 percent of American adults—more than 78 million—are obese. In 2014, VA estimated that 78 percent of Veterans are overweight or obese.
Obesity is a complex health issue to address. It results from a combination of causes and contributing factors, including individual factors such as behavior and genetics. Behaviors can include dietary patterns, physical activity or inactivity, medication use, and exposures to various environmental factors. Additional contributing factors in American society include the food and physical activity environment, education and skills, and food marketing and promotion.
Obesity is a risk factor for heart disease, type 2 diabetes (once known as adult-onset or noninsulin-dependent diabetes), stroke, and some types of cancer. In particular, diabetes and obesity have become a very prevalent combination.
Body mass index (BMI) is a way to assess whether people are overweight or underweight. It is calculated by dividing a person's weight in kilograms by the square of his or her height in meters.
In 2013, VA estimated that more than 165,000 Veterans who receive their health care from the department have a BMI of more than 40, which indicates a serious condition called morbid obesity. Morbid obesity can interfere with basic physical functions and significantly increase the risk of obesity-related conditions.
VA research on obesity looks at the biological processes of weight gain and weight loss. Researchers compare the safety and effectiveness of obesity treatments, and work to find ways to help Veterans keep from gaining weight—for example, through exercise and healthy eating.
VA researchers work hand in hand with the department's MOVE! program, a national weight-management and exercise initiative designed and coordinated by VA's National Center for Health Promotion and Disease Prevention.
The basic cause of overweight and obesity is an imbalance between the calories a person consumes and those he or she expends. Many factors can contribute to this imbalance. However, the rapid increase in overweight and obesity in both the general population and among Veterans over the last several decades suggests that environmental and behavioral influences may now play a greater role than genetics.
The hormone ghrelin—In 1999, scientists discovered that the hormone ghrelin may be the signal that makes people feel like eating. The concentration of ghrelin in a person's blood rises quickly right before a meal, and falls once food is eaten.
In 2002, researchers from the VA Puget Sound Health Care System and the University of Washington in Seattle reported that obese people who followed a six-month diet program and lost a significant amount of weight showed greatly increased ghrelin concentrations in their blood. This alteration in their body's functioning, and the hunger pains that follow, contributed to post-diet weight gain.
Gastric bypass surgery helps people lose weight by changing how their stomachs and small intestines handle the food they eat. The team found that in people who had undergone gastric bypass surgery, ghrelin in the blood plummeted from normal concentrations and didn't fluctuate before or after meals—in contrast to the findings in the diet group. This suggests that the surgery disrupts the stomach's normal ghrelin secretion.
Other studies are in conflict, however, on whether ghrelin levels return to close to normal in gastric bypass patients in the long run, once weight loss has stabilized. European researchers not affiliated with VA have found that sleeve gastrectomies, which involve the removal of part of the stomach, reduce ghrelin levels by an average of 60 percent, and that those levels remain lower five years after surgery.
Eating sweets forms memories—In 2016, researchers at the Charlie Norwood VA Medical Center in Atlanta, Georgia State University, and Georgia Regents University found that eating sweet foods causes the brain to form a memory of a meal.
The study showed that neurons in the dorsal hippocampus, the part of the brain that is critical for episodic memory, are activated by consuming sweets. Meals consisting of a sweetened solution, either sucrose or saccharin, significantly increased the expression of activity-related cytoskeleton-associated protein (Arc) in dorsal hippocampal neurons in rats—a process that is necessary for making memories.
In the future, the team hopes to determine if nutritionally balanced liquid or solid diets that typically contain protein, fat, and carbohydrates have a similar effect on Arc expression in dorsal hippocampal neurons, and whether increases in Arc expression are necessary for the memory of sweet foods.
Fat cell metabolism—Fat cells, or adipocytes, are connective tissue cells that have become differentiated from other cells and become specialized in the manufacture and storage of fat. In a study published in 2016, researchers at the VA San Diego Healthcare System and the University of California found that as fat cells develop, they change the types of nutrients they metabolize (process) to produce fat and energy.
Pre-adipocytes, which are precursors to fat cells, prefer to consume glucose, a simple sugar, to grow and make energy. When they become fat cells, however, they metabolize not just glucose, but also branched-chain amino acids, a small set of the essential amino acids humans require.
Therefore, according to the researchers, fat cells play an important role in regulating the body's levels of branched-chain amino acids, which are typically found in higher levels in people with diabetes and obesity.
These findings may help investigators understand the potential irregularities in the metabolism of fat cells that occur in people with diabetes and obesity, and could lead to new treatments for these conditions.
Bariatric surgery—Bariatric surgeries, which include a number of different procedures performed on the stomach or intestines to induce weight loss, do more than help obese people shed pounds they cannot otherwise lose.
A 2015 study by researchers at several VA medical centers found that the procedure also helps severely overweight patients live longer. The study, which involved 10,000 VA patients throughout the nation, found that the 2,500 Veterans who had the surgery had a 53 percent lower risk of dying from any cause 5 to 10 years after the procedure, compared with 7,500 other severely overweight Veterans who had not.
While previous studies showed that younger, mostly female populations had improved their survival rates after having had bariatric surgery, patients involved in this newer study were older, with a mean age of 52, and were 74 percent male. In addition, 55 percent of those in the VA study had diabetes, and many had other chronic diseases such as high blood pressure, arthritis, heart disease and depression.
The research team is now looking at various forms of bariatric surgery, and whether they help certain subgroups of Veterans. They also hope to learn how long weight loss lasts after surgery.
Transplant drug may reduce body fat—Rapamycin is a pharmaceutical used to coat coronary stents and prevent transplant rejection. In a study published in 2015, researchers at the Malcom Randall VA Medical Center in Gainesville, Florida and the University of Florida College of Medicine found that the drug also reduces body fat and appetite in older rats.
The research team used 25-month-old rats, which are about equivalent in their life cycle to 65-year-old people. They found that after treatment with rapamycin, the rats' body weight dropped by approximately 13 percent.
The drug targets how the body makes leptin, a hormone produced by fat cells that affects hunger and metabolism. (Hormones are chemical substances produced in the body that control and regulate the activity of certain cells or organs.) The researchers hypothesize that the reduction in appetite occurs because rapamycin stops a spike in leptin production that typically occurs in older rats and in humans.
Rapamycin's ability to stabilize the rats' leptin level made them lighter, according to the study team. Overall, rapamycin selectively targeted fat, allowing the animals to retain lean mass. While the current findings are limited to rats, rapamycin has potential as a treatment for age-related obesity in humans because it is already used in organ transplants to keep the immune system in check and prevent rejection of foreign tissue.
Many obese patients feel judged by their physicians. They believe their doctors see them as lazy and undisciplined, and that they are responsible for their own weight gain. As a result, if they fail to lose weight as their doctor expects, they may stay home when it's time for their next checkup.
A team of researchers with VA's Center for Chronic Disease Outcomes Research in Minneapolis and the Mayo Clinic reviewed papers on stigma, bias, discrimination, and prejudice as it relates to medical care in 2015. They found that many health care providers have strong negative attitudes and stereotypes about people with obesity—and that these attitudes influence their perceptions, judgment, interpersonal behavior, and decision-making.
The team also conducted a Web-based survey, results of which were published in 2014, of 4,732 first-year medical students from 49 medical schools, and found that 74 percent of the students exhibited implicit bias against obese people, and 67 percent showed explicit bias. These biases were more negative than those exhibited toward racial minorities, gays, lesbians, and poor people.
The researchers believe that doctors should discuss weight issues with obese patients, but should do so in a less judgmental, more affirming way—making the discussion about feeling good, not about a number on a scale. They also believe that doctors, clinics, and hospitals should have chairs, gowns, blood pressure cuffs, and scales that accommodate patients of all sizes.
Many employers in the United States are searching for ways to help their employees make healthy lifestyle choices. These include encouraging obese employees to lose weight. Some employers offer financial incentives for them to do so.
In 2016, however, a team of researchers from the Corporal Michael J. Crescenz VA Medical Center in Philadelphia and the University of Pennsylvania found that three types of incentive programs were ineffective for promoting weight loss in a randomized trial using weight scales in the workplace.
In the study, the team enrolled 197 obese participants in a workplace wellness program. They were given a weight loss goal equivalent to 5 percent of their weight at enrollment. The participants were randomly assigned to a control arm with no financial incentive for achieving the goal, or to one of three intervention arms, each offering an incentive valued at $550.
Two of the three incentives offered participants the opportunity to have their health care premiums reduced if they lost weight. Participants in the third intervention group could receive prizes in a daily lottery if their weight was reduced.
Twelve months after enrollment, the average weight of all the groups stayed about the same, with no statiscially significant changes among them. According to one member of the research team, the results do not prove that all incentive programs are ineffective, but that more creative designs are needed that might better overcome predictable barriers to behavior change.
One of the main risk factors for type 2 diabetes, a chronic disease in which there is a high level of sugar (glucose) in the blood, is obesity. VA investigators and others have found that sustained weight loss leads to major benefits for those who have, or are at risk for, type 2 diabetes and many other health problems.
Nearly a quarter of all VA patients have diabetes. VA is working to decrease the incidence of both diabetes and obesity among Veterans (see our Diabetes Web page), and to improve care for Veterans with diabetes who are overweight or obese.
Healthier diet and exercise improve glucose control in diabetes—Dietary changes and increased exercise are sometimes not recommended for older adults with diabetes due to concerns over frailty and the age-related loss of muscle mass. In 2016, however, researchers at the Michael E. DeBakey VA Medical Center in Houston presented preliminary findings of an ongoing clinical trial indicating that a healthier diet and routine physical exercise help older overweight and obese adults with type 2 diabetes improve their glucose control, body composition, physical function, and bone quality.
The study randomly assigned volunteers between 65 and 85 years of age to receive either intensive or limited interventions. Those in the intensive group attend 90-minute aerobic and resistance exercise classes three times a week, as well as a diet class once a week where they learn healthier eating habits.
They record all food, drink, calories, and proteins they consume, and can receive individual weight-loss counseling. Control group participants are not given any exercise program and receive only once a month diabetes educational sessions.
At the six-month mark of the yearlong study, all study participants had preserved their lean body mass, but body weight and fat mass of those receiving the intensive intervention had dropped more than the control group's, and their physical performance test and peak aerobic capacity had improved more.
Gastric banding—Researchers at the VA San Diego Health Care System published a study in 2012 that found gastric banding, a type of obesity surgery, nearly always improves or eliminates diabetes symptoms. The researchers followed 66 people with type 2 diabetes who had undergone gastric banding surgery.
Before the banding, all the patients required daily medication for their diabetes. After two years, 48.5 percent had no symptoms of diabetes. Another 47 percent saw their symptoms improve, and only 4.5 percent saw no change in their diabetes status.
Those who saw no change were more likely to have had diabetes for a longer time before the procedure, and were also likely to have lost less weight over the two-year time period following the surgery.
VA MOVE!—VA MOVE! programs throughout the nation offer classes, including both exercise and nutrition information, to help Veterans develop weight management skills. In 2014, VA researchers at the Sioux Falls VA Health Care System studied weight-loss outcomes among 120 Veterans to see if these classes are helpful when participants are at locations other than where the classes are taught.
Half of the Veterans in the study took part in a series of 12 weekly MOVE! classes through videoconferencing. The MOVE! participants lost weight, while the control group, which took neither video nor in-person classes, gained weight.
The average weight difference between the groups was about 12 pounds, and the MOVE! participants kept their weight off a year after their weight was first measured.
Trainer phone calls—A 2013 study by researchers at the Jesse Brown VA Medical Center in Chicago and the University of Alabama at Birmingham found that regular 30-minute targeted phone calls from a trainer can result in significant weight loss for disabled persons.
The nine-month study involved more than 100 participants, each with a disability that limited their mobility. Some of the participants received a physical-activity toolkit along with a Web-based remote coaching tool developed by the research team, as well as phone coaching. A second group received the same tools along with nutritional advice, and a third group got no phone coaching, and received the activity toolkit only after the study was completed.
Those who received the toolkit and the coaching tool lost nearly 5 pounds, on average. Those who also received nutritional advice lost an additional pound—and those who got no coaching help gained an average of 5 to 6 pounds.
Using a personal digital assistant to lose weight—In 2013, VA researchers at the Hines VA Medical Center in Chicago published the results of a study on whether a personal digital assistant (PDA) can help Veterans lose weight. The researchers looked at Veterans with a BMI between 25 and 40 who had been dealing with chronic pain for at least six months.
Half of the Veterans in the study were given a PDA on which they recorded food intake, physical activity, weight, mood, and pain intensity. This group also received telephone support every other week for six months. Weight loss among the group using PDAs was greater than that in the control group at three months, six months, nine months, and a year.
According to the team, self-monitoring of diet and physical activity is associated with weight loss success, and can be performed conveniently using handheld devices.
A study published in 2013 by researchers with the San Francisco VA Medical Center found high rates of overweight and obesity among a relatively young group of Iraq and Afghanistan Veterans—and that obesity rates where highest among those with posttraumatic stress disorder (PTSD) or depression.
The researchers did a retrospective analysis of nearly 500,000 Veterans' health records, and found that 75 percent of Iraq and Afghanistan Veterans were either overweight or obese at their first encounter with VA health care. Most of their BMIs remained stable over a three-year period: some who were overweight or obese continued to gain weight; and fewer who were obese lost weight.
They also found that Veterans with PTSD and depression in particular were at the greatest risk of being obese and being unable to lose weight. This group was also at the greatest risk of being obese and not only failing to lose weight, but continuing to gain weight.
Plasma ghrelin levels after diet-induced weight loss or gastric bypass surgery. Cummings DE, Weigle DS, Frayo RS, Breen PA, Ma MK, Dellinger EP, Purnell JQ. Gastric bypass is associated with markedly suppressed ghrelin levels, possibly contributing to the weight-reducing effect of the procedure. N Engl J Med, 2002 May 23;346(21):1623-30.
Effect of early weight loss on type 2 diabetes mellitus after 2 years of gastric banding. Edelman S, Bhoyrul S, Billy H, Cornell C, Okerson T. Shorter duration of type 2 diabetes mellitus and greater percent excess weight loss were associated with an increased likelihood of remission or improvement in diabetic status through gastric banding after 2 years. Postgrad Med. 2012 Nov;124(6):73-81.
Integrating technology into standard weight loss treatment: A randomized controlled trial. Spring B, Duncan JM, Hedeker D. The addition of a PDA and telephone coaching can enhance short-term weight loss in combination with an existing system of care. JAMA Intern Med. Jan. 28, 2013;173(2):105-111.
The relationship between body mass index and mental health among Iraq and Afghanistan veterans. Maguen S, Madden E, Cohen B, Bertenthal D, Neylan T, Talbot L, Grunfeld C, Seal K. The growing number of overweight or obese returning Veterans is a concerning problem for clinicians who work with these patients. J Gen Intern Med. 2013 Jul;28 Suppl 2:S563-70.
Telehealth weight management intervention for adults with physical disabilities: a randomized controlled trial. Rimmer JH, Wang E, Pellegrini CA, Lullo C, Gerber BS. A low-cost telephone intervention supported with a Web-based remote coaching tool can assist overweight adults with physical disabilities to maintain or reduce their body weight. Am J Phys Med Rehabil. 2013 Dec;92(12):1084-94.
The effectiveness of telemedicine for weight management in the MOVE! program. Ahrendt AD, Kattelmann KK, Rector TS, Maddox DA. Videoconferencing is an effective method to provide the MOVE! Weight Management Program to Veterans. J Rural Health. 2014 Winter;30(1):113-9.
Association between bariatric surgery and long-term survival. Arterburn DE, Olsen MK, Smith VA, Livingston EH, Van Scovoc L, Yancy WS Jr, Eid G, Weidenbacher H, Maciejewski ML. Among obese patients receiving care in the VA health system, those who underwent bariatric surgery compared with matched control patients who did not have surgery had lower all-cause mortality at five years and up to 10 years following the procedure. JAMA. 2015 Jan. 6;313(1):62-70.
Rapamycin versus intermittent feeding: dissociable effects on physiological and behavioral outcomes when initiated early and late in life. Carter CS, Khamiss D, Matheny M, Toklu HZ, Kirichenko N, Strehler KY, Tumer N, Scarpace PJ, Morgan D. Rapamycin has more selective and healthspan-inducing effects when initiated late in life. J Gerontol A Biol Sci Med Sci. 2015 Jan. 23 (Epub ahead of print).
Impact of weight bias and stigma on quality of care and outcomes for patients with obesity. Phelan SM, Burgess DJ, Yeazel MW, Hellerstedt WK. Griffin JM, van Ryn M. Many health care providers hold strong negative attitudes and stereotypes about people with obesity. These attitudes may impact the care they provide. Obes Rev. 2015 Apr;16(4):319-26.
Beliefs about the causes of obesity in a national sample of 4th year medical students. Phelan SM, Burgess DJ, Burke SE, Przedworski JM, Dovidio JF, Hardeman R, Morris M, van Ryn M. Most medical students know that obesity has multiple contributors. Patient Educ Couns. 2015 Nov;98(11):1446-9.
Branched-chain amino acid catabolism fuels adipocyte differentiation and lipogenesis. Green CR, Wallace M, Divakaruni AS, Phillips SA, Murphy AN, Ciaraldi TP, Metallo CM. When pre-adipocytes become fat cells, they metabolize not just glucose, but also branched-chain amino acids. Nat Chem Biol. 2016 Jan;12(1):15-21.
Premium-based financial incentives did not promote workplace weight loss in a 2013-15 study. Patel MS, Asch DA, Troxel AB, Fletcher M, Osman-Koss R, Brady J, Wesby L, Hilbert V, Zhu J, Wang W, Volpp KG. Three incentives failed to promote weight loss, suggesting that employers encouraging weight reduction through workplace wellness programs should use alternative incentive designs to the conventional health insurance premium adjustment approach, larger incentives or both. HealthAff (Millwood). 2016 Jan. 1;35(1):71-9.
Sweet orosensation induces Arc expression in dorsal hippocampal CA1 neurons in an experience-dependent manner. Henderson YO, Nalloor R, Vazdarjanova A, Parent MB. Neurons in the dorsal hippocampus are activated in rats by consuming sucrose or saccharin. Hippocampus. 2016 Mar;26(3):405:13.