Sorry ahead of time, this is going to be a long post!
Let's talk a bit about what causes stalls/plateaus:
The most common reason for any stall (including the dreaded 3-week stall), is simply that you are retaining more Water. There are a few reasons this happens, from hormonal shifts, tissue repair, illness, or changes due to glycogen vs. ketone metabolism. This post would be even longer if I spent too much time here, but suffice it to say that for many people (especially early in the process), they are just retaining water and not actually failing to lose fat.
As you lose more weight, your overall metabolic rate will slow down. People sometimes think fat is not metabolically active, but that's not true. Losing fat means your metabolism slows down, even if you retain the same amount of muscle mass (which most people don't). This means that as you lose weight, it takes less effort to move or even just live, so the amount of calories you burn both during exercise and just living also drops quite a bit.
On the intake side as you progress after bariatric surgery, you'll be able to eat more. This isn't a bad thing and is by design, but obviously you should be able to see the problem here. Your metabolism has slowed down and now you can eat more. This can lead to you basically eating as much as you're burning. When that happens, weight loss stops.
Especially if you're not tracking intake closely by weighing and measuring your food, you can easily be eating a lot more than you think. Some studies have shown people underestimate caloric consumption by several hundred calories on average. This is more than enough to cause a stall.
This one may be TMI for some, but you may simply be retaining more stool. Feeling constipated? That will definitely impact your weight.
This is going to be hard for some people to hear, but I can tell you one thing it's not, and that's hormones. Yes, various hormonal processes negatively impact weight loss in a myriad of ways, but they don't overcome the basic fact that if you eat fewer calories than you are burning, you'll lose weight. What these hormones can do if they're out of whack, is bad things like slowing your metabolism even more, increasing your hunger, screwing with water weight, or even fooling you into thinking you're eating less than you are.
So, that's all great, but what do we actually do if we're in a stall? Well, I think it depends on when it happens and how long it lasts:
If it's early (a.k.a. the 3-week stall), just keep doing what you're doing and you should be fine. I know people don't like that advice, but as I said it's just water, so don't worry about it.
Later on, especially if the stall is lasting longer than 2-3 weeks. that's when I think it's important that you look closely at what you are actually burning, as well as really tracking what you are eating. If you don't know your RMR (Resting Metabolic Rate), you should. The closer you are to goal, the harder it is to get the balance right between intake and output to make sure you're not eating too much, so fixing this starts with knowing your RMR and accurate food logging.
There's a lot of anecdotal advice thrown around about "ways to break a stall", but there seems to be little scientific evidence for any of it. It certainly won't hurt to try things like breaking up your routine in terms of diet or exercise, but just understand that this change may or may not have any impact. If it makes you feel better to be proactive, go for it.
Longer term, there is one piece of solid advice that's backed up by lots of research: Even if you don't really like working out, do it anyway. Those WLS patients that make a regular habit of exercising for 45 minutes to an hour most days a week are significantly more likely to reach their goal and maintain the weight loss. (One caveat here: significantly changing your exercise routine can make you retain water and possibly even add muscle, so don't freak out if you see a stall or even a gain.)
I'll take that exercise advice one step further and say you really should be doing some form of strength training. This is also backed up by lots of studies, but the great thing about strength training is that it makes your burn more calories even at rest (in other words, it increases your metabolic rate). There are lots of other benefits, but the metabolic benefit is the most germaine to the stall question. Those that do strength training are less likely to stall during weight loss and are more likely to reach and then maintain their goal weight long term.
