Calories count: Having too many calories from carbohydrates (and from fat, and from protein) leads to weight gain. It's the calories that make a difference to your waistline, not the carbs.
The exception to this is people who are allergic to carbs. Such people can gain weight from carbs. If you think this applies to you, seek advice from a health care professional.
For most people, a 50-calorie potato is far better, when it comes to weight control, than a 300-calorie steak. Likewise, a 180-calorie hamburger bun is better than a 370-calorie extra meat patty. So while reducing your carbohydrate intake can help you to lose weight by also reducing your overall calorie intake, this doesn't work if you replace the cut-carbs with high-calorie fats.
Cutting out carbohydrates can also mean missing out on vital nutrients from healthy carbohydrate foods which should be part of any well-balanced diet, especially those from fruits, vegetables and whole grains.
If you’re considering a low-carb diet for weight loss, remember to count your calories and make sure you get enough nutrients for health needs - including carbohydrates. Forty-five to sixty-five percent of your daily calorie intake should come from carbohydrates.
One more important thing. Alcohol is in a class all by itself. It is neither carb nor protein nor fat. But there are more calories per gram of alcohol than there are in carb, protein nor fat.