There's some real nastiness and mis-information on this thread!
I am totally at IMLH and her 'how much does a size 18 woman weigh?'! IMLH - I know three women who are or who have been a size 18; my friend, my mother and my aunt. My friend is very tall and is on the lower end of ideal in the BMI measurement, my aunt was clinically obese when she was an 18 (morbidly now) and my mother is just over into the overweight category - she gained weight during the menopause after being slim all her life. I think these 3 represent the various differences in weight that each dress size (within reason) can contain. It is completely ridiculous to estimate health, weight, BMI, fitness e.t.c based solely on dress size.
In the real world various individual weights can carry very different risk factors for various people depending on medical history. I have never been into overweight BMI for example but have a very poor relationship with food and exercise. I have a hypothyroid and a family history of high blood pressure, heart disease, hypermobile joints and arthritis which makes my risks of heart disease as a consequence of poor diet and joint problems generally very great whether I am overweight or not. This leads me to my next point which is that weight/fatness/thinness/dress size(?) is no indicator at all of whether your arteries are furring or joints are failing. Very very possible to be a normal weight and extremely unhealthy with poor joints.
The way to optimise your health outcomes is to be aware of your individual risk factors but primarily to eat a well rounded and balanced diet (including fats and carbs) free from pesticides (as much as possible), chemicals and low in refined flours, sugars and alcohol and take a reasonable amount of exercise. People who over exercise damage themselves just like people who under exercise and your own fitness regime should be tailored individually i.e. for me running is a big no no because of my thyroid and hypermobile joints. What is best for me is a large amount of lower impact exercise such as a moderately high level on the cross trainer for 30 mins 3 times per week in addition to regular walking, weights and cycling.
Breast cancer is also linked to pesticides on food, anti-perspirants, not breast feeding e.t.c. to whoever made the point about being overweight.
My final point is that actually the OP has only said she thinks she is overweight and her DH picks at her about it. I'm not sure this really constitutes abuse, it is very mean but he might not even think she is overweight and may be genuinely, clumsily, trying to help. Just because OP believes she is overweight does not mean she is by any means. Even if her DH thinks she is, this doesn't mean she is either! I had a boyfriend that gave me a 'weight limit' once. He genuinely believed it was the weight at which people are fat - 11st. For me 11st is right in the middle of ideal BMI. He felt I should be 8 or 9st which would make me underweight on BMI charts.
BMI is a rather rubbish indicator anyway since it takes no account of muscle mass or bone structure. For example I have big strong heavy bones and my sister has tiny light birdlike bones, if she was the same height as me and we weighed the same she would be carrying a lot more fat (or muscle! Lol) than I would but we would be the same BMI. This makes it even more worrying that my ex wanted me underweight because I have big bones and will be heavier than average when I am thin whereas my sister has very small bones so will likely be lighter than average when fat. People should look at the bigger picture - being thin (and attractive?!!! ) and having seconds of trifle and wine does not make you fit and healthy (or attractive/productive/nice e.t.c.), being overweight does not make you unfit or unhealthy (or unattractive/lazy/greedy or other offensive adjectives) and it is rather idiotic to show off about thinking being thin allows you to abuse your body without fear because it is likely to fur your arteries and destroy your liver just as much or as randomly as the next trifle-eater or binge drinker.
My friend is very thin and has struggled with hospitalisation for anorexia all of her life. Since she had her son the only way she can keep her weight above the level the doctors start talking about hospitalisation is by only eating very unhealthy things and by drinking an awful lot. Without the calories she gets from this she would be hospitalised but she is not actually eating a larger quantity than before, this is how she manages her illness. Over eating for comfort can be just as difficult to manage and psychologically based as anorexia and lots of comfort eaters share characteristics with bulemics.
Anyway - I would say OP, you should talk to your DH about how this is making you feel, suggest relationship counselling and try to explain to him that it is not the same as counselling for depression (which you should maybe also have separately to the relationship counselling) to try and encourage him to go. I think it is important that you communicate with each other.