You probably recognize the image above, as its the food pyramid from our government's recommended health guidelines for decades. If you look closely you see that carbs are supposed to account for most of the food that you eat. Kind of odd isn't it? Especially since every diet that is popular today, from Paleo to Atkins, tells you to cut the carbs.
Nutritional science is a notoriously challenging field, made harder by attempts to generalize what everyone should eat all of the time. A good example is dietary fat and cholesterol. When obesity first became an issue, there was weak research that showed eating fat makes you fat. So general guidelines were given to take the fat out of food, and we all started drinking skim milk and not eating egg yolks. But food with no fat tastes pretty bad, so food makers started adding sugar. Fast forward to the present and the obesity epidemic is out of control and the incidence of diabetes is at an all time high.
The research now has swung the other way, and most indications are that sugar is a lot worse for you than fat. The correlation between eating fat and getting fat (or having high cholesterol) has recently been proven to be tenuous at best, so much so that in 2015 for the first time ever the government took out the suggestion that people should eat very little of it.
There are other stories in nutritional science that you might find surprising, like the fact that for many people salt has no impact on blood pressure, red meat is fine to eat in moderation, or that spinach isn't the vegetable with the highest amount of iron. Some of the research is so recent that even your doctor might not have seen it.
The point is, you need to be your own advocate. The science is still sometimes hard to pin down, and everyone's needs are different, due to genetics and lifestyle. Thanks to the internet we now all have access to a wealth of information. We just need to make sure that we reference quality sources, and that we also listen to our own bodies.