We also have different rates of metabolism, different stats in life, different influences, different genes. Our lifestyles are different, our views on what's good food is different, there is going to be a massive difference between the ability of some to control their weight than others. It's not about diets, especially useless fads, calorie counting, excessive exercise, or continually weighing yourself. It's just about eating the right types of food in the right proportions. If you stuggle with weight before or after you stop smoking then you may need to look at what you're actually puting in your body, not how much of it. Processed foods are designed to be addictive. The cynicism behind their marketing is almost as bad as the smoking scam, and kills a lot of people before their time as well.
The first thing is not to overcomplicate it. Eat only fresh foods. Even in the current financial conditions there will always be supermarkets that have price wars and loss leaders on fresh fruit & veg. For myself I knew that apples for instance are a great nutrition source but rarely got round to eating one as it seemed like a lot of hard work. At the end I twigged that if I bought large bags of those 'fun size' ones then every time I felt peckish in between meals I could pick one of those up and it would be easy & quick to eat, and completely took away any temptation to eat something unhealthy. I found myself eating a fair few of them during the day as well. This could even be one of the strategies employed to replace any temptation to light up while at home at least..
As with quitting smoking, taking control of your food habits will increase your self-esteem and confidence, knowing that you have the power to achieve whatever you want. If you indicate that you may have an issue with food and are worried about weight gain and temptation to eat where before you'd have had a cig, then the fun size apple trick I mentioned will NOT increase your weight, the fibre, nutrients and slow release sugars will ensure that you eat LESS at your next meal. During the session I'll also get your creative part to come up with other things and activities that will replace the old smoking habit so it will completely fill any perceived possilbe gaps in your experience.
Then just ask me for more information and advice about this area. I can supply some useful tips (no extra charge). Simple, easy ways to get control while still enjoying eating (enjoying food more once you realise what some of the 'staple' stuff does to us and avoiding it like the plague).