AnnPT77 wrote: »

Well . . . not exactly. This will be a long essay (sorry), or maybe rant. There's a TL;DR at the end.

There's some evidence, as I read the research, that repeated extreme yo-yo dieting is bad for health (maybe worse than staying slightly overweight, even).

There are ways that yo-yo dieting can lower one's calorie needs, but it depends on the dieting methods somewhat, and it can be reversible.

Think of it this way: Generally, our bodies get good at what we train them to do. If we're athletically active, like if we run every day, we'll get better at running, right? Bodies be like that.

Over human history, famines were common. The people who lived through them, had kids, were our ancestors. They were the people whose bodies were good at living through famines (unlike the people who died faster under starvation stress). So, we're kind of designed to live through famines, via natural selection.

If we - us regular modern people - go through repeated famines, we're training our bodies to maximize those "live through famine" traits.

Our bodies don't know the difference between repeated famines, and repeated extreme weight-loss diets.

I'll describe a bad pattern that many women in my demographic have done for decades. (I'm old, 66. Times have changed. This may not be what you did, but bear with me. I have a point. Eventually.)

It was common to get/feel fat, then go on a diet. The diet would often involve extreme and unusual tactics: Eating different foods, going for the lowest possible calories we could tolerate. (We felt tough and cool, showing that willpower. It was fun to talk about with friends, sharing "diet tips".)

A common pattern for women was lots of salads and veggies, very low fats, little/no meats, minimized carbs, all low calorie . (We felt delicate and feminine, virtuous even, eating like little birds. That was fun to talk about, too - a bonding experience.)

On the exercise front, plenty of cardio was the norm, back then: Extreme, intense. Aerobics, fat burning zone, all that kind of stuff. No strength training, because we didn't want to "get bulky" or "look like a man". (This was also kind of fun, showing that willpower to do this intense stuff, brag about our workout routines. They were exercise programs designed just for women, so cool.)

Eventually, that would break down, because we couldn't keep it up. Too hard, not compatible with a balanced, happy life.

We "went back to normal". "Normal" tended to be no workouts (or super minimal, still cardio), eating All The Things, but probably mostly carby/fatty things, often still not that much protein: The pizza, the pasta dish, maybe still the salad but with the bits of crispy chicken and the ranch dressing. (I don't know why that's so common, among women my age, low-balling protein foods, but it is.) On the side, soda pop, dessert, wine, beer, sweet mixed drinks, sweet coffee drinks. Snack on the candy, chips. Have the cheesy or deep-fried appetizer.

Repeat, repeat, repeat. What's the effect?

Even without every one of those detailed extremes, each weight loss tends to lose some muscle mass, alongside fat loss (from losing really fast at low calories, not getting good overall nutrition, especially protein, doing no strength exercise to remind our body we need those muscles).

Every regain tends to be mostly fat, no regain of muscle (from still sub-par overall nutrition, too many calories, no activity to encourage our body to use surplus calories building muscle instead of adding fat). Statistically, most people regain to a new high weight, higher than before. It's mostly fat.

Muscle, pound per pound, does burn a few more calories at rest than fat, but the number is small (like around 6 calories per pound daily for muscle, 2 for fat, approximately, so around 4 calories difference per pound per day, just sitting around). That's a small lowering of our calorie needs.

More importantly, that loss of muscle, and the habits the yo-yos create, can have a bigger impact.

The extreme exercise during weight loss teaches us that exercise is unpleasant, even miserable (it needn't be, but it seems like that), plus maybe time-consuming and hard to fit into our life without disrupting our happy routine.

During "go back to normal", we sit around more, get more out of shape, develop a whole range of subtle habits of not moving very much: Not just formal exercise, but maybe things like less window shopping, more TV watching; less active play with the kids, more sitting in the shade with our e-reader.

Those habits lead us to let even more muscle and fitness slip away. The less fit we are, the less fun and the more difficult activity becomes, so we probably do less of it . . . subtly, gradually, unnoticed. Even fidgeting burns up to a couple of hundred calories per day, according to research on fidgety vs. non-fidgety people who are otherwise similar. Who notices how much they fidget? (I don't.)

There are some other subtle things, too: Maybe our body temperature drops a fraction of a degree, because our body's planning for another famine. Feel cold? Maybe our hair grows a little slower, gets a little thinner. (Expected with age, maybe? Or maybe not). Maybe our fingernails grow slower, too, aren't as strong. Those (in this paragraph alone) and other tiny things, technically, might be considered "metabolic damage". They aren't necessarily permanent, either, but they can be a bit stubborn to reverse. Fortunately, they tend to be calorically pretty small.

Bottom line: With a bunch of yo-yos, we tend to burn slightly fewer calories through body composition (less muscle, more fat). We may burn slightly fewer calories from stuff in that "metabolic slowdown" paragraph. We also tend to burn fewer calories - maybe lots fewer - through reduced movement in daily life (plus reduced exercise capability or intensity).

That makes each next round of weight loss a little harder.

The good news: Pretty much all of that is reversible, and we can lose weight without all of that stuff so much kicking us, on the next round.

We can get good overall nutrition (including enough protein, but not just that), add some doable strength exercise, work on cardiovascular fitness gradually via fun (or at minimum tolerable) activities that are manageably challenging to our current fitness level (not miserable or punitive), be intentional about getting more movement into our daily life . . . those can happen when we're losing weight, or when we're not. Beneficial in either case: They gradually improve fitness, and increase routine calorie burn.

When we're losing weight, we lose at a sensibly gradual pace, figuring out how to eat nutritiously and eat enough that our body doesn't immediately slip into "OMG! Famine!" territory. While losing, we can take some breaks at maintenance calories for a couple of weeks, to practice maintenance, but also to let various hunger/appetite hormones recover, so the body can relax its "famine alarms".

During that manageable calorie deficit, we can keep going with the fun, manageably progressive strength and cardiovascular exercise (in ways that fit into our life while keeping enough time and energy for other things important to us - good life balance - so it's sustainable).

Overall, we can experiment, figure out, groove in long-term eating and activity patterns that work for us to stay at a healthy weight, instead of repeating the "extreme loss"/"go back to normal" nonsense. These patterns can become routine habits that happen more-or-less on autopilot, when life gets complicated, because they don't take massive attention or willpower to sustain.

Apologies for the long essay. If you want a more science-explanation, the first few posts in this thread are excellent:

http://community.myfitnesspal.com/en/discussion/1077746/starvation-mode-adaptive-thermogenesis-and-weight-loss/p1

TL;DR: Repeat yo-yo dieting can make each subsequent bout of weight loss more difficult, but for pretty non-dramatic, common sense reasons. The effects are usually reversible, with better plans. Someone who's yo-yo dieted can lose weight, and even reach a point where their calorie needs increase, while having a reasonably happy life during the weight loss, and beyond. That happens with a sensibly moderate plan of good nutrition, modestly reduced calories (for quite a long time), intentional and manageable changes in activity (including but not exclusively exercise).

Best wishes for future success!

1. "Eat until you're 80% full." (The Chinese version changes that to 70%)
2. "1 soup, 3 dishes." (a healthy variety of 1 soup, 2 vegetable dishes, 1 protein dish)
3. "Eat well and worry less."