To reply generally to the things going on in this thread, and to reply to OP.
The "western diet" of the modern world has started leaning heavy on carbs and fats. Asian diet leans on carbs and protein. Mediterranean diet is heavy on protein and fat. Both the typical Asian and Mediterranean diets seem to give less obesity. The easy answer to this is the metabolic process of gaining fat. For your fat cells to open, you need insulin. For insulin to be released, you need carbs. If you primarily eat carbs and protein, fat is missing. If you eat protein and fat, carbs is missing. Going super-low carb essentially makes it virtually impossible for the body to gain fat. There's process called neoglucogenesis wherein proteins are converted to glucose. However, that process demands quite some energy. This means the low carb diet has some merit to it. The issue is that this can affect your brain's ability to perform. Some studies suggest that short term memory is affect, while atkins.com refutes this as being the transitional period to using ketones as fuel.
So, why cut out carbs? Well, it essentially cuts out all trash food. Try getting disgustingly full when you can't eat bread, chocolate or chips. You prevent fat gain, by limiting insulin in your bloodstream. You are also reverting if your body is starting to get insensitive to insulin. Certain stages of diabetes has been shown to be reversible, given a healthy diet. As such, it's an effective way to cut out crap from your life.
But, carbs themselves do not lead to diabetes. That's traditional carbs. Whole grain foods. That's carbs that sustains and fuel you. Have you seen a sugar cane? There's basically no sugar in one. It's all just fiber. The more refined the carbs are, the more dangerous they are to your body. Having a carb-heavy diet in today's society likely means eating a lot of flour that's as close to sugar as you can get it. You may order the bread that looks "brown and healthy" at the deli. Wasn't Subway's "whole grain sub" basically shown to be the least healthy one? It's a minefield of enriched flours and dodgy marketing. It's likely not wholesome, full of complex carbs. What's even worse is that you're likely eating a lot of sugar.
And sugar is really the enemy that's often used interchangeably with "carbs" in this thread, and sugar is no good. There's a good book called "Suicide by Sugar" that I'd recommend. It goes to show just how sugar fucks up your body. It shows how it ruins mineral interconnected processes of the body. Even worse, sugar in the US likely also means a lot of HFCS, where the HF stands for High Fructose. Robert Lustig (
https://www.youtube.com/watch?v=j8zpM7rd2UU) has some incredible light to shine on just how fucked up fructose is. You know how drinking destroys your liver? And how you say that the liver is the filtering system of the body? A substance that only the liver can process is referred to as a poison. Fructose can only be processed by the liver. Even ethanol can be used by cells in your body.
For those saying it's an excuse for lazy people. To you I say fuck you. That's a stupid and ignorant view to take. Sugar is addictive as hell. You can't blame people individually for the health epidemic hitting us. The reason why people were leaner in the 60s wasn't because we weren't as lazy. The genetics were the same. People were just as lazy. We just didn't have that much crap food around us. Now food conglomerates are spending billions annually to ensure that people keep eating their crap food. They keep finding new ways to set you up for failure, and people are told they can stop being fat if they just stop being lazy. If they choose low carb to change their diet, they are actively doing something. Can't that be applauded? That's actually doing something about the situation. What more would you want?