Believe is his food diet is the contributing factor

Rice = Carbohydrate

Carbohydrate will convert to Sugar for Energy
Once it is not in use, it will be converted from Sugar into Fats for your body Storage.
That's why you can see ppl who consume lots of Carbohydrate rich food become very fat.
Make you fat and sleepy.

Eat more protein diet instead..
Protein are also a source of energy for your body.
Let's say you consume huge intake of protein rich food, your body will use it as energy.
Once your body doesn't require it, it will then be converted to urine..

Hence, protein rich food are a better alternative source of energy of your body compared to carbohydrates

This is rather simplified explanation.
If you had studied Biology, this is a very simplified explanation.

Do ur own research
I ain't got time to explain to dumb ppl expecting to be spoonfed

you are the one who is dumb