Rice is probably the most well-known “clean” carb source for bodybuilding purposes.
However, many seem to be ambiguous as to which type of rice is better.
If you read some of my older diet articles, you'll understand why you want carbs to be lower on the glycemic index. Unless you're having them post-workout and need to get carbs processed as quickly as possible.
When you ingest carbs, your insulin levels will spike. The pace and intensity in which they spike depends on based on their glycemic index.
High glycemic carbs that spike insulin quicker and more intensely well help drive nutrients into the muscle faster for those times when recovery ASAP is necessary.
However, when you have high glycemic carbs and don’t need your blood sugar to spike, many of those calories will be shuttled into fat storage than into the muscle.
White rice has very low fat and fiber content, allowing it to spike insulin much sharper than brown rice. Brown rice has more fiber and fat content, which diminishes the insulin spikes it can can.
Because white and brown rice impact blood sugar and insulin differently, the question “Which is better?” can't be answered specifically.
Rather, you would likely benefit more from using white rice in a weakened state (post-workout) when you need to start the recovery process as fast as possible.
Whereas brown rice would be more beneficial for other meals throughout the day where spiking your insulin isn’t a priority.
Neither is better and each have their place in a bodybuilder’s diet. It is simply a matter of using them at the right times for the right scenario.