Body represents a stored version of energy. It is similar to real organisms' fat and muscle combined into one. It helps to increase feeding capabilities while decreasing speed.
Children receive the same proportion of body points of the parent as energy it receives. Thus 10 .repro store will create a child with both 10% of the parent's body points, and 10% of its energy (or that's the goal anyway. Cross your fingers for how effective it will be in inducing specialization and diversification).
Body is important in calculating the power and range of shots. The power of a shot increases linearly with body, while the range increases logarithmically. The amount of body that a bot has can be determined by checking the .body sysvar.
There are 3 ways of gaining body
1: Hunting - Using feeding shots, ie: -1 and -6 shots. DNA command: "-6 .shoot store" and "-1 .shoot store" results in a particle being shot in the direction the bot is facing. If the particle hits another bot, that bot will shoot back a particle containing energy and a small amount of body and waste at the expense of either energy or body. Depending on if it is an energy or body shot.
2: Storing and Retrieving energy to/from body - Bots can store energy as body points with the .strbody command. The value stored into .strbody is the amount of energy to be saved into body. The conversion rate is 10 energy points per 1 body point. To retrieve energy back from body, bots can use the .fdbody command. .fdbody represents how much energy you want to retrieve from body.
There is a limit of 100 energy points per cycle for both storage and retrieval of body points.
3: Energy Overflow - If a bot's energy level exceeds 32000 the remaining energy will be converted directly to body.
Future Energy Stuff
Lots of work is being done in the area of metabolism and digestion. Relatively soon you should see some major changes in this area. These changes will be backward compatible, though, so don't worry about your current bots not working. This stuff isn't in the program yet, but is gonna be added. Such a metabolism and digestion system will result in finer distinction between energy than just energy and body, allowing for specialization.