I eat "normally" so am of a normal weight. I think with the crisps and biscuits thing, if you just don't have them in the house then you can't eat them out of habit. So just don't buy them. And never buy a sharing pack cos its tempting to just keep going!
Have a big but healthy breakfast, it makes such a difference to how I feel mid morning. I have a bowl of porridge in winter or a bowl of muesli with milk and some chopped fruit on top in summer, I usually splash out on blueberries, rasps and straws even when they're out of season. I dont feel hungry till lunchtime if i stick to this. Honestly, the odd time I have had, say cornflakes or even weetabix instead, I am ravenous mid morning in work and if there's any biscuits handy I'll have one.
I also feel massively full after lunch if I take in a sandwich made with my own homemade bread (half white, half whole meal flour). Shop bought bread doesnt fill me up for quite as long. Usually just have cheese and tomato on it. Big load of fruit afterwards. I don't usually get a mid afternoon dip with that - it just makes me ravenous at 6-6.30 so that I enjoy my tea! I usually have a healthy tea (pasta, salmon or curry and rice) and eat enough so that I feel full but not bloated. I eat yoghurt or fruit for afterwards but if I feel full I don't bother with anything for dessert.
I don't ever feel as if I'm on a diet because I'm not, I just eat healthily and never feel like I'm starving myself or denying myself stuff. It's all about getting into good habits. So if you usually have a biscuit every time you have a cuppa then you have to stop. You don't actually NEED the biscuit, it's a habit linked to the tea drinking or whatever.
I will always accept a biscuit or other "naughty" treat if passed round at work from time to time and I eat what I want on meals out or on holiday, there's no way I'd want to be going "oh no I can't, I'm on a diet" - I just eat healthily and normally as a matter of course and enjoy all the goodies or wine I want on a night out.
I enjoy my food and am a normal weight, size 10-12, it's just that I DO stop eating when I'm full and relatives I have who are very overweight I notice will go back again and again to a buffet table. so I wonder if their stomach just becomes used to an overly large amount of food over time? Maybe...
Not sure if that helps anyone but thought I'd post anyway.
Good luck!