What he said to you, during an argument and in anger, is very different than expressing concern about your health. Making comments (I assume, rude ones) and saying that he does not find you attractive, anymore, is not the same as, "Honey, I want you to get healthy and feel great about yourself, again, what can I do to help?"

He said he told me this so that we can save our marriage

So, he's saying that if you don't lose the weight, the marriage is over?

I have gained weight over the course of my relationship with DH. He still flirts with me, touches me all of the time, tells me I'm sexy, he basically still sees me as I was when we met. But, he knows that I'm unhappy about the weight and that I want to lose it, so just today he asked me to tell him if I need anything special from the store and if there is anything he can do to help.

You need support, not asshole comments.

Do what you need to do for YOU.

This is the guy who asked his Mommy what was "normal" for a couple having sex, right? While you were incredibly ill from pregnancy?

I think your DH tries to be supportive but at his core is a feeling of selfish entitlement - that a man has a "right" to sex and to a wife who meets his attractiveness standards.  Lots of men have this core belief, and they don't see how selfish it is because they are convinced deep down that sex is their god-given right in marriage.  And that it's a woman's responsibility to meet that need, and to be attractive for "her man".

He's a jackass to tell you that he doesn't find you attractive. Why hasn't he volunteered previously to watch the kids so you can get back to the gym? He could have done that without any mention of your attractiveness at all, and it would have helped you achieve your goal (and his).  But he can't seem to resist playing the victim a little bit in this area. 

I've just had two babies and I'm in a similar situation physically. My husband bought me some workout equipment and has kept asking me if I've used it but I haven't had a chance because duh... 2 under 2 take up all my time. I'm feeling down about my looks as well. 

These guys want us to do it all and be happy, and skinny, take care of the kids and the house and then get annoyed when we can't do one or more of those things. Usually the kids are well taken care of but our mental and physical health gets pushed aside. Suddenly "you've changed."

The thing is if they supported and helped us more we could do it all. If my DH took on more childcare or house duties I'd be able to workout and feel much happier. Instead we have babies and their lives only change a little and ours change entirely. Then they get mad at us because of it. I make my DH help but I have to ask because I'm still the primary for kids and the house. Oh and did I mention I work too? 

If my DH ever says I've let myself go I will say "No honey, YOU have let ME go."

He should never have blurted out in an argument something he could have said kindly in a discussion.  But it's out there now.  And the thing is, he is expressing something you were already aware of.  But you're mad at him for saying it out loud.  I'm sure you were hoping to find a way to get yourself exercising again, lose the weight, and put it all behind you without him every having to say a thing.  There's a lot less self-recrimination that way.  Would you be just as hurt if he'd said you were drinking too much? or were staying up late playing video games all night and weren't getting enough sleep, or were disturbing his sleep?  Would you be hesitant to point those things out to him?  Your self care is out of balance and he pointed it out.  The elephant is in the room, but as long as no one says it out loud there's a chance that it can be fixed and then it never really happened.

My DH and I both met when we were terribly fit.  Both of us had gone through tough times and were channeling that stress into exercise.  Years later we had both put on too much weight.  It wasn't healthy, and honestly it wasn't attractive on either of us.  Yes we both loved each other, but it was weighing down our moods, our energy, our joy.  So I don't think he's lying when he says he still loves you.  And probably always will.  But it's not fair to tell him he has to be attracted to you no matter what you look like.  You don't have to be a super model.  But you need to find the time for self-care.  To get emotionally healthy by taking the time for you! (An hour or two a day is not unreasonable!).  And physically healthy - so that you have the energy to be the mom and wife you want to be, and yes because he will probably find you more attractive.

You knew yourself that it was a problem, and you've taken the steps to ensure you have the time for yourself now.  Don't hold it against him that he finally admitted something you knew to be true.  And remember to make time for you in the future.  The relationship between your DH and you is just as important (sometimes more important!) than devoting every minute to your small children.  If you two are strong, their world is stronger.

Wow, your H is a jerk.  If he was truly concerned about your health, or acting out of love, he would have brought your weight up gently and with concern and offered to help in whatever way he could.  Making comments about your weight during a fight isn't expressing concern; it's intended to wound.  He deliberately aimed at an area he knew you were uncomfortable with and he succeeded in hurting you.  And of course it hurts to learn that his love is conditional - otherwise why would your marriage need "saving" simply because you gained weight?  Did he think that somehow the fact that you were 60 pounds heavier had escaped your notice, such that he needed to point it out?  No, he's just an ass, plain and simple, and he's scrambling with his excuses about telling you "for love."

In your situation, this is what I'd think about doing.  First, if your husband thinks your marriage needs saving from your weight gain and no longer finds you attractive, I would say that the marriage isn't on solid ground.  There is no way I'd be a SAHM in a situation like that.  I would put those babies in daycare and find a job, or if you don't have good marketable skills, I'd get some training/go back to school.  Put yourself in a position where, if your husband decides there's something else he doesn't like about you or your appearance and decides to leave or makes you want to leave, you can support yourself and your kids. Second, since you're unhappy with your weight and feel unhealthy, I'd make it my mission to address that as soon as possible.  But I would be doing it for ME, not H.  In my experience, weight loss is 90% diet.  While exercise and working out is great and has many benefits, meaningful weight loss is not one of them for many people.  Exercise ups your hunger, which can increase your eating.   Dieting is hard, but it doesn't require a big time expenditure.   And it sounds like you enjoy working out.  Pull out the stroller and take your kids for nice long walks.  Getting out is good for your mental health. Tell your husband that he needs to be on baby duty when he's home so you have time to go to the gym or use your home equipment uninterrupted.  (If you're home, lock the door and put on headphones so the kids don't interrupt- let H deal with them).  I work out almost every day, and my DH happily handles (or at least handles) the kids for an hour or two while I go to the gym.  I don't need to lose weight, but working out is a stress reliever and my baby (aaaah, I guess she's a toddler now!) is a chunk, so extra strength helps. DH knows it's in HIS best interest for me to have time to work out.  You should also insist that your husband handle the kids for at least a few hours a week so you can do other fun things for yourself, like hang out with friends or engage in a hobby.  He's not the only one working - you're working hard and for longer hours than he does.  You need to make yourself a priority.  
 

Your DuH is an arse. I had twins and the only way I got any time for me was when dh got home every day. He took over for an hour every evening. I had them ready for bed and he got an hour of quality bonding and loved it. He also appreciated the fact that I was calm and serene afterwards. It's about being a team and working together, not about making demands of your partner. There, I said it, partner as in partnership... 

Good luck to you, OP. 

I feel so hurt and angry for you. I am overweight as well and I will tell you this: there are many men out there that would be attracted to you simply for you, not for your weight but because of you, your mind, your personality, your curves.... Your DH delivered a low blow in my opinion. If he was truly concerned, out of caring for your health, for example, he could have said much nicer words and offered to help you effectively so you could have time for you to work on you. I would suggest next time leaving the house for your workout and forcing your DH to take care of his kids on his own. Start forcing time for you in the family schedule. For example, Tuesday and Thursdays, your DH handles the kids and dinner while you do you, outside of the house. Go for a walk even. Go window shopping. What do you enjoy that you could turn into exercise? Then also take a good chunk of time on the weekend too. Your DH needs to step up as a parent and parent his kids without you, and you, darling, need to let him. Do not control this, just leave the house.