When I worked as an outpatient dietitian, I remember many women saying how at 40, it was like a flip switched and they started gaining weight. Being in my twenties at the time, I had a hard time relating.
There’s no doubt that weight gain is a common complaint at midlife. A study published in Preventative Medicine found that among midlife women (40-59), nearly 40% of those with a BMI less than 25, desired to lose weight. And for those with a BMI over 25, 90% wanted to shed pounds.
But here’s the thing. Chasing after weight loss at midlife can do more harm than good.
After discussing hormonal changes at midlife, I’m digging into physical changes. This will help you see why weight loss can be tricky.
A Woman’s Changing Midlife Body
My weight seemed to settle in a comfortable place after having kids. Not my pre-kid weight, but it was where my body wanted to be. It stayed this way for several years. Then during regular doctor visits spaced over a few years (I don’t weigh myself at home), I saw it inching up. One time it was up four pounds another time five.
Research confirms that midlife women tend to gain weight. In one study following midlife women (42-52 years at baseline) over six years, there was a 0.6% annual jump in weight which added up to about 6.5 pounds in the six-year period. This coincided with a 1% loss of muscle mass.
Most research in this area links overall weight increases at midlife with lifestyle changes (decreased activity, less sleep, etc.) and the effects of aging (decreasing metabolic rate due to body composition changes). But the menopause transition which includes declining estrogen is thought to be the culprit behind higher body fat.
During this time fat can increase 2-4-fold, and preferential storage is in the abdomen, often called intra-abdominal fat. This link is thought to happen because estrogen regulates adipose tissue and protects against fat accumulation. When it declines, fat storage can increase. Abdominal fat is a watch out because it is considered an endocrine organ due to its secretion of substances linked to insulin resistance, type 2 diabetes, and the metabolic syndrome. This is not weight dependent.
About 2 years after a woman’s final period, everything slows down and the body seems to stabilize in terms of body fat and weight gain. But the menopause and post-menopause period is a time of rapid bone loss. Early postmenopausal women can lose as much as 1.15% of spine bone mass and 0.85% of femur neck bone mass each year. This declines in the late postmenopausal period to 0.20 and 0.57%, respectively.
Not everyone experiences body composition changes in a similar manner. Although this generally holds true for white and African American Women, Chinese and Japanese women don’t seem to gain as much body fat and lose as much lean body mass.
Addressing the Why Behind Weight
Back to my midlife weight gain. I brainstormed about what could be the underlying cause. My eating and sleeping hadn’t changed. There were stressors, but I was dealing with them.
Then it dawned on me that after quitting my job at the hospital, I didn’t move as much. I was great at getting workouts in but sat a lot of the day writing. At the hospital, I walked constantly. Come to think of it, I always walked at various jobs and while living in New York City. I also knew that muscle mass decreases with age and I still put a preference on running and cardio over strength training.
So, I began taking walking breaks throughout the day and put weight training more regularly in my routine and felt more energized. About a year or so later my weight was back down to where it was before. It had settled back to my post-kid weight that it seemed to prefer with more activity.
Other reasons women gain weight at midlife may be a lack of sleep, new medications like antidepressants and responses to stress. Then there’s eating in the absence of hunger which can be due to stress, boredom or a response to restrictive eating and/or dieting.
In short, weight gain may be a sign that some part of a woman’s food regulation is off. And at midlife, the way the body regulates changes, which needs to be factored in.
Rushing into Weight Loss
But I could have gone another route. That is if I panicked and tried to shed those nine pounds. Maybe I’d try keto or some other diet. Or maybe I’d cut out all sugar, eat only clean, and vow to not eat between meals. I’m sure I’d lose weight but there would be a cost.
Research shows that quick weight loss induces both losses in fat and lean body mass. With this type of intentional weight loss, for every pound of fat loss, roughly a quarter of it would be lean body mass. And because my BMI is lower, I’d also be likely to lose some bone density in the process. For a midlife body that is already losing muscle mass, and will lose more bone in the future, this isn’t good.
In time, the strict diet that induced weight loss would prove difficult to maintain and I’d likely gain the weight back. In an attempt to gain back the lean body mass my body knows is important, it will first act to recover the fat stores I lost, and this will make me “out of control” hungry. By the time the muscle is recovered, I will have more fat than when I started.
But if I’m older than 60 or don’t exercise or have an inadequate diet, I may not recover the muscle loss. A study in the European Journal of Clinical Nutrition uses the term “collateral fattening—a process whereby excess fat is deposited as a result of the body’s attempt to counter a deﬁcit in lean mass through overeating.”
This process is more pronounced in leaner people because they have less fat, to begin with. Lean body mass is vitally important as we age and the body works to spare it anyway it can. And because fat is protein-sparing, it comes along for the ride to ensure less is lost.
Focus on Body Composition instead of Weight
Research reveals that at midlife, BMI doesn’t reflect health risk, body composition does. We can try to lose weight but what are we actually losing? Isn’t it better to focus on a healthy lifestyle and improving body composition? You can be thin but have high abdominal fat and low muscle and be at a higher weight with more muscle and less abdominal fat.
Like it did for me, making changes may result in weight loss if that’s what the body wants. Either way, any weight loss is likely to be slow, which is beneficial. That’s because not all weight loss is created equal.
For example, in one study with middle-aged, sedentary men and women, some restricted calories, another group restricted calories with exercise, and the final group only exercised. After losing the same amount of weight, the individuals in the exercise-only group did not lose lean body mass.
Research suggests more modest weight loss spares lean body mass and bone compared to quick weight loss and reduces intra-abdominal fat. It’s also important to realize that women are not meant to be the same weight all through adulthood and weight that goes up does not have to = bad.
In fact, one study following over 300,000 healthy, middle-aged adults over the age of 40 for nine years found that those with modest gains in BMI had the lowest risk of all-cause mortality, cardiovascular-related mortality, and non-cardiovascular mortality. This is compared to those who had BMI fluctuations, weight loss, and even those whose BMIs stayed constant.
The researchers stated: “To this end, we speculate that any BMI gains observed in the metabolically healthy individuals might have conferred a protective effect against the risk of CV and non-CV mortality.” They also think lean body mass has something to do with it, which is higher in people who don’t lose weight: “Lean body mass could, therefore, be a feasible explanation for why BMI loss carries a higher mortality risk, whereas BMI gain might be associated with a better clinical prognosis.”
What to do
I will dig deeper into how to use exercise, nutrition, and emotional health to keep the midlife body as healthy as it can be. I’ll be interviewing a lot of experts too. But for now, just know losing weight can work against the body’s changes at midlife.
Instead, focus on a strong healthy body and meet any weight gain with curiosity. It can be freeing to move away from that number on the scale that says nothing about health and well being!