Final answer:
Caffeine increases the metabolic rate within minutes, maintains the elevated rate for a couple of hours, enhances fat breakdown, and can improve both aerobic and anaerobic athletic performance.
Step-by-step explanation:
Caffeine is a well-known central nervous system stimulant that can affect metabolic rate and athletic performance. Regarding the influence of caffeine on metabolic rate, several points are noteworthy:
- Caffeine can indeed increase metabolic rate almost immediately after ingestion, often within 15 minutes.
- The increased metabolic rate can persist for 2-3 hours following caffeine consumption.
- Caffeine has the ability to enhance lipolysis, which is the breakdown of fats into free fatty acids, partly due to increased catecholamine release.
- However, the claim that long-term caffeine use effectively reduces body weight lacks consistent support; while caffeine may contribute to short-term weight loss or prevent weight gain in some individuals, it is not a substitute for diet and exercise.
Regarding athletic performance, caffeine can improve both aerobic and anaerobic activities by increasing energy availability, reducing perceived exertion, and delaying the onset of fatigue. It also increases fat oxidation, particularly in those with low physical fitness levels.