Carbohydrates are bad for you!
In the 1980s, fat was the undisputed enemy. In 2017 however, the media has found a new scapegoat: carbs. Making alarmist blanket statements about carbs now appears to have become a national sport!
In fact, depending on your point of view, the glycemic index and the insulin index seem to rank foods by how dangerous they are. Like cholesterol, insulin is often misunderstood as being unilaterally harmful.
Our bodies need and produce both substances. Cholesterol is important in the production of many vital hormones and insulin is required to store glucose (the sugar in your blood) or use it for energy.
Evidence from the early days of research in this field suggested that carbs caused insulin insensitivity. This can be true in diabetics and in insulin-resistant people overeating carbs, but not in healthy people on a healthy diet.
Although we agree that modern eating habits often tend to involve overdoing it with carbs, it is (as ever!) a question of portion control. Many carbs are indeed delicious and quick to prepare, but they are also relatively low in nutrients and do not fill us up for long.
Cutting carbs (especially processed carbs) can be a viable fat-loss decision, if it helps you eat less. But if cutting carbs makes you miserable and always hungry, you should consider other options. If you want to lose weight, what matters is not to replace fat by carbs or carbs by fat, but to end most days on a calorie deficit.
The Truth: Carbohydrates have been demonized long enough. As long as you don't overindulge, starches are not inherently harmful.
Fats are bad for you!
Eat fat, gain fat, right? For many decades, the traditional way to lose weight has been to subject oneself to a low-fat diet. But as studies pile on, research piles on, and old wisdoms sometimes have to give way. Today, we know that, just like eating cholesterol isn't likely to increase your cholesterol levels, eating fat isn't what makes you fat.
Far from being healthy, shunning all fat from your diet can be dangerous, since your body needs to consume at least some omega-3 and omega-6 fatty acids.
As for the myth that saturated fat causes cardiovascular disease, it is just that: a myth. At the end of the day, trans fat is the only kind of fat that has been shown to be unilaterally detrimental to health — a little won't kill you, but avoid it if you can.
The Truth: If you stay in a caloric surplus, a low-fat diet won't make you lose weight, especially since it can decrease your testosterone production. You need some omega-3 and omega-6 fatty acids, saturated fat won't give you a heart attack, but too much trans fat may.