It’s probably not. Excluding rare and serious metabolic conditions, which should be diagnosed by a doctor, people’s metabolisms tend to be within 200-300 calories of each other.
A review article of 67 scientific studies found that “when adjusted for differences in fat-free mass, resting energy expenditure values in obese and non-obese individuals tend to be comparable” and that there is “no association of baseline resting energy expenditure with weight change among 775 men during a 10-year period”. The review draws the conclusion that “Regarding metabolic factors, available data indicate that although there are variations in resting energy expenditure and in the thermic effect of food, there is little evidence that these variations contribute significantly to the observed trends in weight gain.”