At alternate times both the media and the neighbor or the mother-in-law come up with food recommendations that everyone, even us, by dint of hearing about them end up believing: real dietary myths that have nothing to do with good and healthy habits, but they seem to us roughly right. But they are bullshit. These are things that haven’t been scientifically backed up, but how many of us know they’re not true? If you are among the many who recommend these things, if you have found them written in some blog or even in the newspaper or even worse in some nutrition book, do a serious experiment and try to collect reliable studies before recommending them again.
You will be amazed to see that there is no scientific evidence or that, when they do exist, they often affirm the exact opposite of what we believe.

DIET MYTHS: THIS IS WHAT IS NOT TRUE FOR SCIENCE
Raise your hand if at least once in your life you have not heard that:
1) After 18.00 you do not eat carbohydrates (or you get fat):  on the contrary, studies of 2011 established how eating carbohydrates at dinner is even healthy. There is no study that has established that after a certain time (any) food is fattening, let alone a macronutrient. The legend derives from the idea that carbohydrates “bring energy” that are useless at night, so they turn into fat. However, not all carbohydrates are created equal, and our ability to convert what we eat into fat also depends on our metabolism and what we have been doing throughout the day.
2) Breakfast is the most important meal of the day: there are certainly many studies in favor of breakfast, but none that have established that it is an essential meal for staying healthy, or even the most important of the day.
3) You need to eat little and often to raise the metabolism: there is no standard number of meals to raise the metabolism. In this regard , the meta-analysis conducted by Alan Aragon , which collects all the studies that have associated the number of meals with weight loss, is worthwhile.
4) Pasta makes you fat:There is no study that establishes that pasta makes you fat, worse still that gluten makes you fat (or hurts, obviously leaving out those who are celiac or have a known sensitivity, known as gluten sensitivity). Conversely, a recent study associated eating pasta with lower BMI and a leaner waistline.
5) The blood group determines our diet:  the blood group diets (in Italy that of Dr. Mozzi) have not been supported by scientific studies. Few studies conducted so far on the link between blood group and disease have led to different outcomesfrom those of the various diets of the blood group (and limited to the capacity for which people with certain blood groups can get sick of certain diseases or have conditions more or less favorable to risks, especially of the cardiovascular type ). But in no case has it ever been possible to establish ad hoc diets for different blood groups.
6) Salt is bad: how many times have we heard it said? In reality, one thing is not to overdo it with salt, another is to avoid its consumption a priori, as many recommend. Eating without salt or with less salt than the normal dose can lead to worse health risks than excessive consumption.
7) You cannot mix different proteins in the same meal:I couldn’t find any scientific research here that proved that mixing protein in the same meal is bad for you or makes you fat.  Zero. 
8) You need to drink at least 8 glasses of water a day. There have been studies that found that people who drank fewer than three glasses of water a day could be at increased risk of early mortality. But no studies have confirmed a recommendation that comes from the 1940s. Read here the whole story of how this urban legend was born, it’s worth it.