It’s tempting to blame our weight problems on a slow metabolism, even as we pop another potato chip into our mouth. The truth is, a faulty metabolism rarely is to blame for being overweight. In fact, our bodies are just too efficient for our own good.

“We have evolved through many, many years of starvation and deprivation to become very metabolically efficient, so during times of feast and famine, we could run on very few calories,” explains Dr. George Griffing, a SLUCare endocrinologist and metabolic specialist. Those genetic changes evolved through millions of years, he notes, and “in the last thousand years, with the development of technology, those genes actually are working against us.”

Griffing does not offer a rosy outlook for those trying to outwit their metabolism. The problem is, as we decrease calorie consumption, metabolism declines to protect us from starvation. Our body thinks it’s doing us a favor, and it is ever more diligent as we age.

“As we get older, we lose muscle mass. Our vital organs also don’t require as much energy as they did when we were younger. Thus, more mature bodies do not burn calories as efficiently as younger ones,” says Dr. Kenneth Poole of Mercy Clinic Internal Medicine in Clayton.

Griffing expands on the point by offering an automotive analogy: “Over time, our bodies have become like a Prius, and our gas consumption is very efficient,” he says. “Now, all of the sudden, we’re filling our tanks up with excess amounts of fuel, which is spilling over into the back seat and into the trunk. Now we need to find a way of burning that fuel. We’re trying to convert our Prius into a Hummer.”

Despite the fact that most people are metabolically healthy, there are occasional misfires in the metabolic system. Common signs that your metabolism is not working properly include changes in energy, heat or cold intolerance, changes in hair texture, unintentional weight gain or loss, and/or stool changes. “Thyroid dysfunction is perhaps the most common metabolic dysfunction in adults,” Poole says. “However, conditions such as diabetes, pancreatic dysfunction, musculoskeletal, and small and large intestine dysfunction can also affect metabolism.”

For the majority of people who are struggling to lose weight against their own efficient metabolic mechanisms, Griffing says that the only real answer boils down to the energy-in/energy-out ratio. There has never been a single metabolic study in which subjects on a calorie-reduced diet fail to lose weight, he notes. Yet the catch-22 is that obese individuals tend to be even more metabolically efficient than others. In other words, as an obese person restricts calories, the metabolic rate tends to decrease faster than it does if a thinner person diets.

“The most important thing that you can do for yourself is to eat a balanced diet, rich in vegetables and fruits, and get in the habit of exercising regularly,” Poole says.