A study looked at why some people seem to never gain weight no matter their diet.

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Genetics can play a significant factor in a person’s ability to easily lose weight. Getty Images

A new University of Cambridge study may have an answer to the question asked by many frequent dieters: Why can some people eat anything they want and never put on any weight?

In a study published Jan. 24 in the PLOS Genetics journal, university researchers in the United Kingdom compared the DNA of 1,622 thin volunteers, 1,985 severely obese people, and a normal-weight control group of 10,433. They found that thin people have genetics on their side.

“Using genome-wide genotype data, we show that persistent healthy thinness, similar to severe obesity, is a heritable trait,” the researchers concluded in their “Genetic architecture of human thinness compared to severe obesity” study.

Dr. Eddie Fatakhov, a board-certified internist, nutritionist, and co-author of “The Doctors’ Clinic-30 Program” and “Dr. Fat Off – Simple Life-Long Weight-Loss Solutions,” said many studies have compared gene variants from obese patients to patients of normal body weight, but only two previous studies explored the genes of thin people.

“This study is the largest study that has compared the genetic variants among thin people to the control group of normal weight and severely obese patients,” he said. “Based on this study, researchers were able to create a genetic risk score for the development of obesity later in life.”

Participants studied for their thinness had to have a body mass index (BMI) of less than 18, be in good health, and have no medical conditions or eating disorders. The researchers gathered saliva samples for DNA analysis. The participants were asked questions about their general health and lifestyle.

“I haven’t seen many studies looking at this population,” said Dr. Mir Ali, general and bariatric surgeon at MemorialCare Orange Coast Medical Center in California.

But despite the role genetics may be playing in obesity and slimness, the doctors stress the importance of other factors that can be controlled.

“Genetics does play an important role in determining somebody’s weight, but we don’t want people to think that that’s the only thing that determines somebody’s weight,” said Ali. “There are things that can be done.”

At the top of the list, of course, is exercise. However, our technology-centric society, with all of its modern conveniences, is presenting challenges to people getting up and moving around, said Ali. He recommends at least 30 minutes of exercise 5 days a week.

“Getting regular, consistent exercise is very important,” he said. “It doesn’t have to be strenuous activity… but just consistent.”

He said that some studies have shown that even gardening for 30 minutes a day can improve health.

“It’s just getting outside and moving is the important thing,” he said.

In addition to exercise, Fatakhov said there are other things people can do to control weight.

He advises people to avoid phthalates over concern it may increase the risk of weight gain. He also recommends increasing daily fluid intake to 3.2 liters for men and 2.2 liters for women, and increasing fiber to help make you feel full and [it] also provide prebiotics that are beneficial to the microbiome in the gut, which may also impact weight.

“Take it one day at a time,” he said. “Sustainable weight loss is a marathon not a sprint. It does nobody any good if you lose 30 pounds, then gain it back 6 months later.”

He said to find medical experts when you need help, and to try keeping a food journal.

He said there is hope for people out there who are battling with weight.

“They can seek out physicians that are trained in obesity medicine or specialize in weight loss,” he said. “There are currently several drugs in clinical trials that are promising for overweight/obese patients that we could not imagine even just five years ago.”

Fatakhov said that obesity is a disease and those who are struggling with it shouldn’t be blamed.

“It should be treated seriously just like any other potentially progressive disease,” he said. “Also, discuss with your doctors hormones that may affect your weight, such as thyroid, low testosterone, and estrogen predominant patients.”

When it comes to dieting, Fatakhov said to ask yourself two questions:

“Can you see yourself doing this diet for the rest of your life?”

“Would you recommend this diet to your children?”

If the answer is yes to these questions, he said, this is actually a lifestyle change that is worthy to pursue, and not dieting.

Even though the study shows a genetic component to weight, a healthy lifestyle is not out of your control.

“People can control the environment to a certain extent and be cognizant of what they are putting in their bodies,” said Fatakhov. “There are several studies that show that exercise along with lifestyle and dietary modifications will help, and maintain the weight loss.”