Yes, they do. I have spent a lot of time online looking for reasons why. I didn't find any good ones to convince me I might be missing out on any essential nutrients if I don't eat bread or pasta. Of course, grains give us a ready source of energy, but what if I already have plenty of energy stored away on my hips and thighs?
Then I realized bread is probably the world's oldest processed food. So old, that we don't even think of it as a processed food any more. It is a staple that we take for granted. It's hard - especially at first - to imagine living normally without eating bread.
I also spent a lot of time looking for the nutritional benefits of bread. Conventional health wisdom tells us that it's good to eat wholewheat bread. Certainly, it's better than white bread. However I have baked a lot of bread myself, and I know that even a wholewheat loaf tastes way better when it has a substantial portion of white flour in it. Often wholewheat bread is little more than white bread with bran thrown back in. So you're not eating a whole grain.
As such, there are no essential nutrients in that bread that you need for optimal health. It took me a while to realize that.
Then I spent time looking up the nutrients of other grains like quinoa, millet, barley and the like. They are undoubtedly better for you than a similar quantity of bread. But they also contain a lot of sugars. That's something to keep in mind. You might want to continue to eat them in controlled quantities, or you may choose to eliminate them almost altogether, like I have done. It's up to you.
At the end of the day, weight loss occurs when you use up more calories than you consume. Carbs give you a burst of energy, and then your blood sugar dips and you become hungry again. At such times it's easier to reach for a starchy snack with a high glycemic load like a cookie or a glass of pop to make you feel good again. Portion control is very hard for many people, and most of us are much more sedentary than our ancestors were. This is how weight creeps up as we get older, especially after we reach middle age.
When you reduce the glycemic load in your diet, you won't experience the ups and downs as much and you won't feel as hungry when your body hits the down. Ultimately weight loss comes from reduced calorie intake, but by getting off the grain ride, you can make it easier.
Another way to put it is that something has to give in order to lose weight. By eliminating the non-essential food choices, it leaves more space for the foods that are better for you and which won't leave you wanting to eat more than you need to.
This, in a nutshell, is why I don't agree with the nutritionists who recommend eating 6-8 portions of carbohydrates every day.