brianastree

Yes, I can see an entry for Solarium Bistro Dinner as $0 under Cruise Planner.

I always bring , never had issues.

If you go into the description of the activity it should be under "Know Before You Go"
Hopefully they will have put this in all activities that have an additional fee but the app is still a bit hit or miss with details at times

While prescription masks do exist, it is pretty rare that an excursion would have them available.  It would be best to try to find one that is customized for your nearsightedness and bring it with you on the cruise.  You can order them online or find a local dive shop to assist you.  
You won't be able to get the proper seal on a mask while wearing glasses unfortunately.  I feel your pain as I am nearsighted as well and absolutely would not be able to see anything without corrective lenses.  I rarely wear contacts, but snorkeling is one activity where I do.

Our rule is "if it's not the best <whatever> you've every had, stop eating it!" I don't like to waste food, but I more don't like to see my waist get bigger.
Also, we never, ever take the elevator. Sometimes we have to take a break going up, but we just plan the time for that. (In fact, sometimes it's much faster to use the stairs -- like after the show gets out and there's a crush waiting for the elevator!)
Get up for 7am stretch class! Then you're already moving for the day.

The one exception being if you have purchased The Key, where they will take carry on luggage directly to your room and you can get to it after 1pm. But you'd still want to keep anything valuable or necessary with you. This won't apply to many, but it's one of the perks I did like.

Anything you want to use prior to about 4-5pm on embarkation, you'll want that in your carryon.  Also remember you'll be carrying whatever you carryon with you from 10am to 1pm if you embark as early as is possible.  So you want that luggage bin approved carryon luggage?  Its coming with you all through the ship as you explore, go eat something, go to the pool, etc.  
I recommend your carryon be something the size of a backpack and MAYBE a tote bag at the most.  When you start dragging luggage all through the ship, I think it winds up dragging you down for 3 hours.  
Also remember any wine or a 12 pack of soda/water that you want to bring, MUST be in your carryon luggage.  So consider the weight of that as well if you bring 2 bottles of wine and a 12 pack of soda.  That's a pretty heavy load and that's before you add anything like swimwear, medications, change of clothing, etc.

Yes, you have to check anything bigger than a carry on with a porter.  If you need something on embarkation day put it in your embarkation bag in case your luggage shows up later in the day.

I can only imagine what people who do world cruises do. They are at sea for three months or more. I gained 5 lbs on my one weeks cruise in Jan. So if I did a world cruise eating the same way I would gain around 60lbs! Ha ha. Obviously if a did a world cruise I’d have to be on a stricker diet. 

We are fortunate that we don`t gain weight on long cruises. Lucky or whatever.  Do what all the previous posts have recommended.  First and foremost is to hydrate all day long.  Eat smart. Hit the gym if you can.  Ride the bike, walk on the treadmill.  Walk outside on the upper deck.  A strong wind offers great resistance. Hot weather makes you sweat.  We have yet to be on a cruise and see the gym crowded.

First , the Gym is free  (allow 16 years old and above) , most of  the classes cost extra.
Regarding the opening time , it depends on the ship but you can count on at least 6 AM to 10 PM , in some ships it will be opened until 1 am .

Is access to the gym (I am an elliptical user) included with the cruise price?  Is it open 24/7 or only certain hours?  Are the classes mentioned above an added cost (spinning, etc.?)  Do they carry Splenda on board? 

One of my tips is if you do specialty dining, half the portion you're given and ask them for a to-go box immediately.  Out of sight out of mouth!  Or ask for a child's portion.  That way you can still enjoy all of the wonderful tastes and not feel deprived when there are amazing smells wafting around, but still keep to your goals.  
Drink at least 2 glasses of water before food goes into your mouth.  Helps to fill up your stomach.  Veggies first, then protein, then starch, then fats.  Ask for a double helping of veggies!  More veggies on the plate, the less deprived you feel.  
Dessert options stick to sorbets and fruit.  You can also ask for a sugar free option as well.  They'll definitely have these for diabetics.  And they do help with feelings of deprivation.  If everyone at your table is snarfing down cake, and you're sitting there with folded hands sipping away on water.... that's a fast track to binge eating later.  
The biggest thing with the food, fill up on hearty fibrous veggies like broccoli, spinach, etc.  Lettuce isnt going to fill you up and make you feel satisfied in the long run.  Not to mention there's a lot of temptation on that salad bar.  Dressings, bacon, eggs, legumes... they all taste wonderful but they're calorie killers on the salad bar.  Tell them to remove the bread basket from the table.  Out of sight, out of mouth!  
Big thing for me and dieting is not feeling deprived of food.  It sure sounds easy just to eat less, but when you're in a high temptation environment like a cruise, just eating less is an unrealistic expectation.  Salad is wonderful dont get me wrong, but its not going to fill you up unless you have those hunger busting fibrous veggies in the salad.  They help fill you up and help you stay full!
 
Now, for the exercising.  Walk everywhere.  The elevator is your friend only when carrying your luggage.  Otherwise, stairs all the way.  Do the dance lessons onboard.  They help keep you moving!  At the pool, jump on in and play!  I think as adults we've really neglected the power of play.  Play keeps us active so let loose!  Feel free to enroll in a spinning class if your fitness level is up to spinning.  Aerobics classes, free weights, machines galore.  Hop on the treadmill or elliptical and enjoy the amazing views.  You'll completely forget that you're exercising when enjoying such amazing views.  
 
Now for the overall health.  Get good rest.  Easier said than done when you're excited on your cruise!  But remember, healthy mind healthy body!  Reward yourself with a massage or facial or other spa treatment.  Sticking to a diet on a cruise is hard work!  So have that reward massage!
 

I'm glad you wrote this, because I was going to post something similar. Based on this "3 up 3 down" rule, it is a great idea to choose a cabin on a deck that is about halfway up. 
If your cabin is too high or too low, than many of the trip will involve a LOT of climbing. That's a good thing, if you can handle it. But if the climb is too far, many people will opt for the elevator. Choosing a mid-level deck will help defeat the laziness and enable an "I can do it!" attitude.

My husband and I also do a couple of things.
1. We order room service breakfast (free).  It is continental.  We order the night before, get up early hit the gym, or walk the track (taking the stairs).  Stop at WJ, and get an omelet since we know we have continental will show up within minutes upon returning to our cabin.  Take the stairs back down.  This keeps us away from piling on at WJ. 
2.  We eat dinner late.  We go to the WJ when it opens for dinner.  We make 2 plates .  One is our appetizers while we get ready for dinner, shrimp, veggies, etc., anything we can pick at it while we shower and dress, which fills up our stomachs.  The other is our late night snacks (typically a deli/cheese plate that we put in the min-fridge and something sweet)  The thing is by doing so, when I go to dinner, my eyes are not bigger than my stomach.  Again this is pre-planning.
3. I do specialty restaurants, but from a weight issue,  I like the MDR more.  In the MDR you will have the same server every night.  By day 3 they know your likes and dislikes, iows, your eating habits.  The MDR usually offers the wedge salad, 1x during the cruise.  However, bc I have sailed with RCCL multiple times, and use the MDR often, I ask on night 1 can I have the wedge salad the next night?  I have never been told no, even though it is off the menu.  My husband knowing my eating habits will chime in and say, can you give her that in a child's portion, bc otherwise I am the one left eating it or it is wasted food. 
I also order multiple appetizers.  I will order a salad or soup as an appetizer, and ask for the calamari (appetizer) for dinner. 
No offense, but point being it really is up to her.  I am in my 50s, keeping weight off is a battle.  Going on a cruise with booze and unlimited food makes it even harder.  Yet, I have never gained a pound.  I attribute this to planning.  I could take the elevator.  I could sleep in.  I could not ask for off the menu meals at the MDR. Notice it is all I could.  
Not trying to offend. Just saying she has options to stay on the path.  For me, the splurge night is not lobster, but lamb shanks.
 
 

I've been doing kept since June, on Oasis last week I ate and drank "normal" and gained 10lbs!  I've lost 3 of the 10 so far!  

My DW made a rule. If we are going up three decks or down three decks, take the stirs. Otherwise the elevators. My fitbit recorded quite a few floors walked.

We're also consistent stair users.
Also 100% agree with the water consumption! It is sooo easy to get dehydrated quickly.
But, I find the biggest impact to the shrinking clothes phenomenon is what we eat for breakfast and SUGAR. It is so easy to walk into the Windjammer and pile it on for breakfast and that's when your body is looking for calories to intake and store. Keep the breakfast in check! Fruit, some cereal and some protein. Hash browns, bacon, biscuits, danish, omelet, etc...just beggin' to cause you to break out the stretchy pants. Sugar, stick to low sugar desserts and minimize the sweet drinks.
We did a B2B last month for a total of 14 nights...I was up four when I came home, so not too bad this time, but it has been MUCH worse before. ?

I have to reiterate use the stairs every time.  I will be honest, that is what we do.  It was only on our 4th cruise that I used the elevator.  We were on a family cruise, and I remember remarking OMG they have the day of the week on the floor, how cute.  1 family member said to me we have been on this ship for 5 nights, and now you are just noticing?  My response was, this is the 1st time I have taken the elevator on any cruise.  
Don't know which ship you will be on. but you will be amazed how many times a day you climb the stairs.  It will start day 1.  You can wait for an elevator after the Muster Drill or you can walk the stairs and get there quicker
IMPO, drink 2x as much water as you do at home.  Between the sun and alcohol you will dehydrate faster than just hanging at your desk at work.  
I have never gained a pound on a cruise.  I am a grazer.  Lots of small meals.  Lots of water during the day. I do the deluxe beverage package, but with every drink I get a bottle of water.  I do not order a new drink until I have guzzled down that bottle of water.  

I don't have any tips but I applaud her for wanting to lose weight on a cruise. 
I've been on Weight Watchers and I've done pretty well, I'm hoping I will be at my goal by the time my cruise comes around, but I plan to enjoy myself (yup, bought the drink package) and eat well but not everything in sight.  I do plan to take stairs and do lots of walking so hopefully it won't be too bad.  Either way I'll be back to the gym once I'm back home.  Which brings up the point there is a gym on board if she wants to use it.  They're supposed to be really nice.  

Outside of the already great ideas, my suggestion is to ask for low sodium meals.  I think the many meals on RC use a ton of salt  (to be fair most restaurants do the same).  I think you can do all the above and bloat just due to the amount of sodium.  Drinking lots of water helps but she may want to watch the sodium too. 

My tip is eat at the same frequency you do at home.  On a cruise, I feel because food is all over, I just end up eating more often (regardless of healthiness of the food). 

Choose a cabin as far as you can from the elevators. 

There's an acupuncture to lose weight option on the cruise planner at the spa.

I cut out SOME excess sugar, and walk as well as use the gym very frequently.  As others have also stated I also use the stairs quite a bit as well, our last cruise to AK had me going from the bottom deck to the top using the stairs.  Once I got to the top I would go to the other side of the ship and go down the stairs and come back up the other side I would do 3-4 laps per day, during the cruise and managed to actually loose a couple of pounds rather than gain.