As
@lovinglife pointed out Knowing what makes you overweight and being able to do something about it can be difficult, particularly if you have metabolic and/or other health issues. I have always been overweight and, when I was 20, tried a vlc diet that, after 2 months and hardly any weight loss, nearly killed me because my metabolism went into starvation mode and started to shut down some of my organs to protect the most vital ones to the extent that my GP told me to go home and eat a good meal! Following tests my endocrinologist told me that I was one of his few patients that could honestly blame their metabolism for their weight so, after realising that I would not lose weight, I followed what I thought was a healthy diet ie low sugar, low fat, wholewheat everything inc bread, pasta and rice, jacket or boiled potatoes, 5 pieces of fruit .......... until diagnosed with hypothyroidism, and starting medication for that, and T2 and changing to a lower carb diet. I have since lost weight, slowly but surely, but still have more to go.