After getting the beginner 40 during college, my weight loss trip was a long one, because I made so many mistakes. Many of them were diet related, including eating too much in general (holy 800 calorie smoothie!), Eating too many carbohydrates and not enough protein and exaggerating it on high calorie “health” foods like nuts. But I also made many fitness-related mistakes that actually led to weight gain ! If you want to be narrower with training, experts agree that you avoid these training errors.