Microbiome Resource Center
Microbiome Resource Center
August 01, 2018
3 min read

Microbiome may hinder weight loss in adults with obesity

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A gut microbiota with an increased capability for carbohydrate metabolism was associated with a decrease in weight loss in patients with obesity and overweight and underwent a 3-month comprehensive lifestyle intervention program, according to results of a pilot study.

“The way that we have looked at obesity, or people who are slightly overweight, has been to try lifestyle interventions,” Purna C. Kashyap, MBBS, a gastroenterologist at Mayo Clinic, told Healio Gastroenterology and Liver Disease. “[Lifestyle intervention] is usually a combination of exercise, diet and behavioral therapy. The goal is for us to try to get patients to lose weight by doing these lifestyle modifications, [but] we realize that the effect is going to be modest.”

Kashyap noted that while some diet and exercise programs are highly successful, others are not.

“Our usual approach would be to assume that people who are not losing weight are not doing what they are being told,” Kashyap said. “That’s the stigma associated with people who are not able to lose weight. And, I think that puts people in a negative space. Because if they’re truly doing everything that they’re told and are still not losing weight, then people view them with suspicion and say, ‘you’re not doing what you’ve been told,’ and it leads to demoralization.”

Kashyap and colleagues recruited 26 adults (mean age, 53.5 years; 81% female) from the Mayo Clinic Obesity Treatment Research Program between August and September 2013 to participate in a lifestyle intervention program for weight loss to assess if other factors contributed to people not being able to lose weight while following the 12-month program.

“We have looked at a lot of other factors in the past in terms of genetics, the environment and behavioral state and we know that all of those contribute to some extent,” he said. “But, what we haven’t looked at is the microbiome.”

Microbiome findings

Adults aged 18 to 65 years with a BMI between 27 kg/m2 and 39.9 kg/m2 who were able to provide informed consent were included in the study.

Individuals were excluded from the study if they had health problems that prevented them from participating in physical activity, previous operations for managing obesity, or use of weight loss medication within the previous 30 days.

The mean weight at baseline was 95.7 kg, and the mean BMI at baseline was 34.1 kg/m2. A 5% or greater weight loss after 3 months served as the primary endpoint.

During the first 3 months, researchers followed participants through weekly 1-hour sessions, biweekly in the fourth month, and monthly thereafter until the conclusion of the 12-month program.

The researchers collected fecal stool samples at baseline and after the first 3 months of the program.

“We focused on the first 3 months knowing that there was significant contact with patients where they were being met with weekly, so we [knew] that compliance was being closely monitored,” he said.

At 3 months, the mean weight loss was 3.71 kg (95% CI; 2.31-5.11) and the mean reduction in BMI was 1.27 kg/m2 (95% CI; 0.69-1.87).

Nine of the participants lost at least 5% of their weight from baseline after 3 months. The mean weight loss was 7.89 kg (95% CI; 6.46-9.32) in the success group and 1.51 kg (95% CI; 0.52-2.49) in the group that lost less than 5% of their weight.

Microbial compositional analysis using the linear discriminant analysis (LDA) effect size (LEfSe) method identified two members of the gut microbiota that were significantly different between the groups. Phascolarctobacterium was significantly increased at baseline in participants who lost at least 5% of their weight after 3 months (P = .008) and Dialister was significantly increased in those who achieved less than 5% weight loss (P = .03).

“We didn’t see a change in the microbiome, at least over 3 months, which is fairly short in terms of big shifts in the microbial populations,” he said. “What we did find was that, when we look at individuals who are not able to lose weight, their bacteria were more capable of being able to use energy from carbohydrates.”

Personalization in weight loss

Kashyap said that the results reiterate the idea that ‘one size fits all’ does not work.

“We realize it depends a lot on an individual’s microbial makeup in terms of what diet may be most effective for them,” he said. “The first thing for us is to be able to individualize treatment options for people based on the microbiome, which plays a role in these interventions. It’s not going to be important for every intervention, but in this case where we are trying to change the diet of an individual and we know that the bacteria are intimately involved with their diet, it becomes an important factor.”

Kashyap mentioned that the results need to be validated in a larger cohort and the researchers are recruiting more patients.

“There are multiple approaches that we can take to try and get people who are not able to lose weight, which is either adapt the dietary intervention to their microbes, or to try to move the microbes to a state where they are able to lose weight,” he said. – by Ryan McDonald

Disclosure: Kashyap reports no relevant financial disclosures.