You’ve heard people swear that they “eat like a bird” but still gain weight, while others “eat like a horse” and remain slender.  A new study proposes that obesity is driven more by exactly what we eat, and not as much by the calories we consume.

For decades, nutritional experts have maintained that if you consume more calories than you burn, you’ll gain weight. According to Futurism.com, the study results published in The American Journal of Clinical Nutrition, refutes that standard philosophy of weight gain.

The scientists found that a carbohydrate-insulin model, or CIM, is likely the cause of obesity. The CIM says that a diet that increases insulin levels is what leads to the accumulation of fat, regardless of the number of calories. Carbohydrates, particularly highly-refined carbs and excess sugars, increase insulin levels and cause more weight gain than other foods. The researchers point out that we’re eating too many foods with a high glycemic load, which are quickly digested and raise blood sugar levels. High glycemic foods are usually highly processed products that trigger hormonal responses that tell our bodies to store more calories as fat.

The model suggests that the intake of processed carbohydrates and starchy foods leads to changes in the levels of insulin and other hormones which causes increased fat deposition, according to Medical News Today.

 Dr. David Ludwig, an endocrinologist at Boston Children's Hospital and co-author of the study, said that during the popular low-fat food era, people consumed more processed foods which may have led to our current obesity epidemic. By eating whole foods instead of processed products and following a commonsense exercise program, weight loss may be more achievable.

Dr. Gabe Mirkin, author of The Healthy Heart Miracle, tells Newsmax that eating fiber-rich foods helps produce healthy bacteria in the gut that breaks down soluble fiber into short chain fatty acids that are readily absorbed and help reduce insulin and cholesterol.

“On the other hand, refined carbohydrates are absorbed in the upper intestines and cause a rise in blood sugar, insulin, triglycerides and cholesterol,” he says. “The insulin makes you hungry, so you eat more.”

Dr. Alexandra Sowa, founder of SoWell Health, which specializes in preventive health, nutrition and obesity meditcine, tells Newsmax that the study underscores her philosophy of weight loss.

"This study supports the CIM which underlies the whole foundation of SoWell Health,” she says. “Weight loss is not rooted in ‘eat less, exercise more,’ but in understanding how your body’s specific biology responds to hormones, like increased insulin levels triggered by processed foods, specifically carbohydrates.”

Sowa, a dual board-certified physician specializing in internal and obesity medicine, says that the CIM states that we increase fat storage as a result of consuming processed carbohydrates and not necessarily increased caloric intake. This leads to weight gain and is primarily responsible for elevated obesity rates around the world.

According to the Centers for Disease Control and Prevention, the U.S. obesity prevalence is a whopping 42.4%. Obesity-related conditions include heart disease, stroke, type 2 diabetes, and certain types of cancer.

“I estimate that 88% of Americans have evidence of metabolic dysfunction which means their bodies are not hormonally balanced and not able to keep a balance of ‘calories in and calories out,’” says Sowa. “For this reason, most people will fail traditional calorie deficit diets, but will be responsive to a higher-quality food diet, one that focuses on healthy proteins, fats, and whole grains along with minimally processed carbohydrates.”