All-cause weight gain, except –
**Core Concept**
The question tests the understanding of factors contributing to all-cause weight gain. Weight gain can be attributed to various factors, including increased caloric intake, reduced physical activity, hormonal imbalances, and certain medications. The question requires the identification of the exception among the given options.
**Why the Correct Answer is Right**
Weight gain is a complex phenomenon influenced by multiple factors. However, certain medications, such as corticosteroids, are well-known to cause weight gain due to water retention and increased appetite. Corticosteroids stimulate the hypothalamic-pituitary-adrenal (HPA) axis, leading to increased cortisol levels, which in turn promotes fat storage and water retention.
**Why Each Wrong Option is Incorrect**
**Option A:**
This option might seem correct at first, but certain medications like antidepressants, antipsychotics, and some antihypertensive agents can indeed contribute to weight gain.
**Option B:**
This option is incorrect because certain medications like corticosteroids, as mentioned earlier, are known to cause weight gain.
**Option C:**
This option is incorrect because it is a known exception among the given options. However, we still need to know what it is.
**Clinical Pearl / High-Yield Fact**
To remember the exception, consider the mnemonic "CORT" - Corticosteroids, Obesity, Reduced physical activity, and Treatment (of certain conditions). This mnemonic helps to recall the common causes of weight gain and the exception among the given options.
**Correct Answer:** C.