Health Bar
From The Blockheads Wiki
A Blockhead's physical condition is displayed on its Health Bar.
Where Located
A health bar is displayed next to a Blockhead's reference icon on the left side of the screen as the upper bar with a red heart on its left. It is also displayed in the menu for eating food as well on a Blockhead's full status window.
Decreasing
A Blockhead's health is reduced by physical injury (such as from falling or animal attack) or environmental issues including eating too many chillies, running out of air, or becoming too hot or cold.
Increasing
Eating something will usually restore health as well as relieving hunger.