My response is usually... "Thank you... healthy food choices, a lot of sweat and the helping hand of weight loss surgery." 

Every now and then I get "Ohhhh surgery huh my friend's cousin's sister's hair stylist had THAT surgery and gained it all back" or "Ohhh I lost xx pounds on my own." My answer depends on my feeling of their intent (mean, snarky or just clueless, lack of education about WLS) 

Mean & clueless I don't waste energy.

I hadn't really thought about this, I also kept it quiet except for close friends that I trusted.  My mother in law didn't even know (though, she's been verbally judgmental in the past...)  Anyway, I will probably say that "Eating right, exercise and hard work really does pay off.  Thank you for the compliment!" then walk off.  Or, depending on who they are, ask them if they are interested in surgery... then give them the link to OH

I just said I had changed the way I was eating and didn't eat sugar, gluten or refined carbs any more.  Totally true.  I don't usually discuss my surgery because it really isn't anyone's business and I really don't think anyone really cares.

After a while it becomes your new normal and people don't mention it, don't even notice it.  After the first year I haven't had anyone really say anything.

I have worked at my job for nearly 3 years and no one there has ever seen or know me as obese.  I have talked about my surgery if the subject comes up but I talk about it matter of factually and don't really elaborate.  It's a non issue.

Recently I was talking to a co-worker who is fairly new and she mentioned that she used to weigh about 400 lbs and she had the lap band and I told her about my surgery.  

My favorite is when someone finds out I've lost 120 lbs and they say "You don't look like you have ever been that heavy."  Really?  What does a person who lost weight look like, a deflated balloon?

Topless....yes they do look like a deflated balloon. Hahahah! 

Any way a person does it takes hard work!! Nothing worth doing or having is easy! I have been battling weight issues all my life. I got serious in 2008 and lost 108 lbs doing weigh****chers and it was hard work. I gained over 80 lbs of that back and just had R&Y in March of this year. I have lost 60 lbs of that 80 + lbs since starting the process of WLS. It has all been hard work! So, with that said when people say oh you look great I say to those that don't know or that I don't feel like telling them I had WLS.  Thanks, I have really been working at it and it takes a lot of hard work! I leave it at that.

My close friends, co-workers and family know what I did, but they also know I have to work hard at what I am still doing to make this successful. WLS is not a free ride!

Well, you could always go for smartassery:

The Dig Food diet- it works!

I no longer need to eat. I subsist on air and light.

I've stopped eating anything that tastes good.

I'm straight out about it because I like to bust the myth that wls is for a bunch of lazy people. My ***** vibe must be pretty strong, though, because most people don't ask.

People will stop asking once they get used to the new you. I also cultivate an attitude of 'Move along-nothin' to see here'.

I have lost about 160 lbs and I get asked questions all the time about it by people that when I was 300lbs would snub me I generally respond with "Its amazing how choosing to be healthy can change a person. So, how often do you work out?". STOPS them dead in their tracks. Now, if its someone that I can tell is genuinely curious (as in my heavier ladies that ask not for some sort of drama filled personal gain, but for advice) then I am much kinder and will talk to them. 

"I  follow a personalized plan worked out between me and my doctor" which is a true statement.  But now, I just feel like a liar.  

_You are not a liar. You are keeping your confidential health information to yourself which is totally legal and encourage by such legislative acts such as HIPPA.

Continue to say thank you. And give them the gist of what you do (i.e. 3 meals a day, protein forward, no starches, 1/4 cup non starchy veg and I work out doing x yz, 5 times a week).

I agree that they are out of line wiht their questions though.  Part of me thinks the world is so desperate for something that REALLY WORKS, that the desperation makes the brain cells misfire or something. At least for me, that was what was true. I didn't do WLS surgery for 10 years. Instead I watch the successes and failures of my braver cousins that DID have the procedure.  It wasnt until I was convinced that it would work did I go under the knife.  I think people (in general) are tired of being on the diet merry-go-round and just want a way to get off of it.

I just said I watched what I ate and exercised.  Which wasn't a lie. 

I take exception to people thinking I have cheated because I have a band.  In the beginning I was exercising 90 minutes a day 6 days a week and that didn't include my daily walks at lunch.  I worked damn hard to get this weight off and I won't have someone belittle my accomplishment by acting like my weight loss had nothing to do with what I decided to put in my mouth and how much sweat I poured out daily. 

Although, I have a problem at work where there is another lady that got Lapband and wasn't quite so successful as I am.  She is struggling like many Banders and hasn't lost much weight.  They like to compare us.  I don't like it.  Sure I am the one they are praising.  But I feel the need to defend her and educate them.  I tell them it's not as easy as it seems.  I told them to Google Lapband failures and then wonder why she isn't doing well.  Grrrr!!!  I hate that they out me in this position.  Do you know at one time they were watching how much and what she ate and reported it back to me.  I said, I don't want to hear it...you have no idea what is going on with her medically with that band.  It's like they don't hear me!!!

My secret fear is that one day I will gain weight and I will become the butt of their mean whispers

Those people sound nosey AND malicious.

Congrats to you for not letting them pull you into their cesspool.

One can't compare. Different surgeries, amounts to lose, goals and outcomes!