Am trying to reduce my weight. People suggested me to take oats instead of rice. Which is the right time to take oats for a good effect. Breakfast or lunch or dinner?
Oats aren't medicine. They are a food and such a source of calorie, more specifically mostly carbs. Oats won't magically make you lose fat, in fact if you eat too many calories -from any food- you will get fatter. Focus on your overall calories and eating balanced meals while staying in a deficit and you will lose fat.
You should eat both rice and oats, no need to choose or substitute.
The GI of foods is determined under experimental conditions after an overnight fast, and might not apply to foods consumed later during the day because glycemic response is strongly influenced by the composition of the previous meal, particularly when meals are consumed within an interval of few hours. Indeed, it has been shown that a high-GI breakfast cereal (GI = 124) elicited a lower increase in blood glucose concentrations at lunch than at breakfast. Also, the difference in glycemic responses induced by the low- and the high-GI breakfast cereals at lunch were lower than that predicted by the large difference in their GI, which was determined at breakfast
The reason oatmeal is good for promoting weight loss is because it is high in fiber and low in fat. The high fiber content helps keep you full for a long time, reducing the desire to eat soon afterwards. According to this site,
the fiber in oats forms gels to fill up. And it is these gels that delay the emptying of your stomach so that you don’t feel hungry quickly.
It seems to me that this should be true at any point during the day. I've done a little research and found a few sites that recommend eating oatmeal for breakfast, but I haven't seen any reason why the benefits you get at breakfast wouldn't extend to other meals. Perhaps it's because breakfast is the first meal you eat, and so oatmeal helps reduce hunger early which lasts throughout the day. But given that you will eat more than once, it might be beneficial to eat oatmeal for breakfast and then as part of your other meals as well.