**Core Concept**
Basal metabolic rate (BMR) reflects the energy expended by the body at rest to maintain vital functions. It is primarily influenced by body composition, particularly fat and muscle mass, with higher muscle mass increasing metabolic activity.

**Why the Correct Answer is Right**
Obesity is characterized by excess adipose tissue, which has a lower metabolic activity per unit mass compared to muscle. Since fat tissue contributes less to energy expenditure than lean mass, individuals with obesity exhibit a reduced BMR. This is due to the lower thermogenic effect of fat and reduced mitochondrial activity in adipocytes. Thus, despite higher total energy stores, the metabolic rate per kilogram of body weight is diminished.

**Why Each Wrong Option is Incorrect**
Option B: Hypothyroidism (not listed as "Hypehyroidism") would cause decreased BMR, but the option says "Hypehyroidism," which is a typo and likely meant to be hyperthyroidism. Hyperthyroidism increases BMR due to elevated thyroid hormone levels stimulating metabolism. So this option is incorrect due to incorrect terminology and opposite effect.
Option C: Feeding increases energy intake but does not reduce BMR; in fact, post-prandial metabolism rises temporarily.
Option D: Exercise increases metabolic rate acutely and chronically due to muscle hypertrophy and improved metabolic efficiency, thus raising BMR.

**Clinical Pearl / High-Yield Fact**
In obesity, the metabolic rate per unit body weight is lower than in lean individuals — a key reason why weight loss can improve metabolic function. This is why BMR is often underestimated in obese patients, and metabolic syndrome is more common in such individuals.

✓ Correct Answer: A. Obesity