Energy is a measure of how much the player can do before getting exhausted, represented by a blue half-circle bar at the top of the screen. Almost every action, including walking, will consume some energy. If the energy bar is ever depleted, the player will pass out and respawn back at the camp. Passing out also removes all buffs, but has no other penalty. Energy is replenished by eating food or by resting at camp. Eating from the stew will restore half of the energy and reduce energy cost for 6 hours.
Because the player will need more energy as they progress in the game (mostly for combat and rowing) but have limited inventory space for meals, they need to discover meals that restore more energy. The amount of energy restored by meals depend on the tier of fish used in the recipe, with the higher-tier fish being found farther from the camp.
Walking and running
Walking consumes a small amount of energy over time. If we consider one side of a 6x6 plot farming area to be 3 meters, then every 12 meters walked will consume approximately 1/72 of a full energy bar. Running increases both speed and energy consumption by about 33%, so it is faster but less efficient. (The previous paragraph might no longer be correct as a lot of energy cost has been changed in 1.02.)
As of 1.02, a player sleeping during sunrise will automatically wake up and gain a buff that will last until sunset (a little less than 12 hours). While under that buff, walking is free and running is cheaper.
Eating foods cooked with Ginger Root will decrease these energy costs for a while.
Using the shovel consumes a high amount of energy, and using the bucket consumes a low amount.
Eating foods cooked with Cane Sugar will decrease these energy costs for a while.
Throwing a fishing line out for the first time will consume a small amount of energy, as will each individual pull when reeling the fish in. Reeling in a fish with few strong pulls (which is when the two ripples overlap) is much more efficient than many small pulls.
Eating foods cooked with Allspice Powder will decrease these energy costs for a while.
Each row in the rowboat will consume a moderate amount of energy, so going as straight towards a destination as possible while avoiding getting close to land that will slow the boat is generally a good idea.
Eating foods cooked with Fresh Thyme will decrease these energy costs for a while.
In combat every few swings of the sword will consume a small amount of energy, and getting hit will consume a moderate amount.
Eating foods cooked with Chili Flakes will increase the damage the player deals, requiring fewer swings and therefore saving energy, and eating foods cooked with Black Pepper will decrease the energy lost when hit.