The brain, like the rest of the body, depends on steady fuel and proper maintenance. As people age, several common factors can quietly affect brain health. Older adults often eat less overall and may skip meals unintentionally. Protein intake frequently declines, even though protein needs remain the same—or increase slightly—with age. Intake of fiber, healthy fats, and key vitamins and minerals may also fall short. At the same time, sleep tends to become lighter or more fragmented. Physical activity often decreases. Thirst sensation weakens, increasing the risk of dehydration. Many older adults also take medications that affect appetite, digestion, or the absorption of nutrients. Individually, these changes may seem minor. Over time, however, they can contribute to low energy, irritability, low mood, confusion, slowed thinking, or forgetfulness, often without one clear cause.