There are quite a few things you need to look at, other than being a smoker and how much you eat.
How much you eat, might not be as important as WHAT you eat. If you're eating lots of things with refined sugar, flour, pasta, etc, it will be hard to lose weight, because those things are digested quickly and turn directly to fat, if not used promptly for energy.
Exercise is critical - you have to use up the calories you eat.
If you drink sodas, switch to water or unsweetened tea; if you need a sweetener, switch to Stevia in place of sugar. Switch to low/no fat milk vs whole milk; switch to whole grain breads and pastas vs white bread and regular pasta. Opt for mostly veggies on your plate, because most are calorie free, unless you put lots of sauces, cheese, etc on them. Make sure you get lean protein with every meal; and don't forget to include some "good" fats, such as those found in nuts/seeds, olive oil, avocados, etc.
Other things to consider are medical issues, such as hypothyroidism, insulin resistance, and/or PCOS. All 3 of those conditions affect how your body handles the food you eat. The thyroid controls metabolism, heart rate, body temperature and other functions. Insulin is considered the "fat storage" hormone, so if your body doesn't use it properly, you will store fat a lot easier. PCOS is Polycystic Ovarian Syndrome and affects the reproductive hormones, which also contribute to weight gain/inability to lose.
You should make sure you don't have these underlying medical conditions.
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