I'm not a qualified nutritionist, so please use your own discretion before you follow whatever I say. This is purely based on my intuition and experience. My goal is to stay fit and active. I'm not looking for weight loss. So my principles may not apply to you if you intend to lose weight. Okay....enough of all the disclaimers :-)
There has been an increasing trend of many people eating only salads for dinner. "No carbs in the night for me", "I don't take rice, I eat only chapathis" - such comments have become quite common these days.
The most important factor when it comes to dinner is the timing - how much gap do you give between dinner and your sleep time? I usually eat my dinner at 8 PM and go to bed by 10:30 - 11PM. So there is enough gap for 2.5-3 hours for the food to get digested. I have come across people who proudly say they eat only chapathis for dinner but then go to bed immediately after finishing their meal. So eating chapathis and hitting the bed is only causing more harm in the form of bulging pot bellies, disturbed sleep, general sluggishness during the day etc.
After sunset, our digestive system slows down and it is advisable to eat easily digestible foods such as aapam, idli, idiyappam, dosa, rice etc. If you are a North Indian, the recommended foods would be rotis with light dal and avoid heavy lentils like channa or rajma, paneer etc.
Ayurveda recommends eating fresh fruits, raw vegetables and sprouts in the morning and afternoon hours. They are rich in fibre and micro-nutrients. During the morning/afternoon hours, our body's ability to absorb these nutrients will be high. Our body has enough time to absorb and assimilate the raw foods.
Fibre-rich foods need more time to digest and that's precisely the reason why we don't feel hungry for 3-4 hours after eating whole grains or raw foods. Then logically speaking, doesn't it make more sense to eat such fibre-rich foods during the day if you are planning to lose weight?
Whenever I have just a salad for dinner without any carbs, I find it difficult to do any workout the next morning. It also makes me feel groggy. I don't avoid carbs but I eat less carbs in the form of a small cup of rice or 2 plain rotis.
The bottom line is
(1) eat easily digestible foods for dinner - simple, home-made foods that your genes are attuned to
(2) give 2-3 hours gap between dinner and bed time
(3) eat fibre-rich foods like raw vegetables and fruits during the day
(4) eat carbs at night ; be conscious of the serving size