Hi OP, I'm 5'3 125 41yo and started lifting weights last year just before spring break. Happy to report this year my arms and lower body are super toned and my waistline has shrunk a good amount. My clothes fit loosely now. I still weigh the same!
I lift 4-5 days a week and didn't change my diet all that much. I did start getting noticeably hungrier a few weeks after starting the routine, I just tried to eat more Greek yogurt for breakfast, and generally eat a more plant-based diet, like using beans as mains. But I still eat a good amount of carbs I think probably more than people would approve of.
Don't overthink the diet, honestly a little fat is a good thing when you're in your 40s. Keeps you looking youthful. I had a bout of depression after having one of the kids and lost my appetite and 10 pounds and even though I was a size 2 for a while, boobs and butt were pretty deflated and overall sad. That depression led to a self-punishing phase of eating lots of crap and subsequent weight gain (but disproportionately in the belly, oh cruel fate), which then set me on the lifting journey.
My advice is first and foremost find a lifting routine that motivates you (for me, it was peloton), and let your body and intuition take care of the rest.

Are you currently lifting and not making gains? I’m eating a calorie deficit and making gains so you definitely don’t NEED to eat more…

https://www.washingtonpost.com/wellness/2023/07/19/light-weight-lifting-strength-resistance/

"The new large-scale review of past research, published in the British Journal of Sports Medicine, ... analyzed 192 past studies comparing different versions of weight training to no resistance exercise, hoping to tease out the single, most-effective combination of weights, sets and sessions to produce the greatest gains in strength and muscle size.

But there wasn’t one. Any type and amount of training worked to build strength and mass, they found, and to about the same extent. Whether people lifted heavy weights or much lighter ones, several times a week or only once, repeating their sets of exercise once or twice or thrice, and whether they were men or women, 18 or 80, they generally gained substantial strength and muscle mass."

Do something that challenges your muscles - weights, machines, bodyweight, whatever you prefer. Prioritize movements that use large muscles. Do it to a point where the last rep is quite challenging. Everything else is details that don't matter much.

Then, and this is the hard but crucial part: Do it regularly (at least 2x a week, preferably 3-4x). (But it doesn't have to be the same routine.) Progress will probably be slower than you expect, but will last much longer - at least two or three years, if you continue to increase the weights (or reps or sets).

Anonymous wrote:

Anonymous wrote:Personally I think the whole bulk and cut is crap. Just start strength training and increase protein.

This is OP and yes this sounds way too complicated for me. Is there a calorie and protein goal I should start with? How do I figure this out? And how frequently should I be heavy lifting?

Actually this is the least complicated of any of the suggestions thus far. You're not training to be a bodybuilder OP, so it really is not that complicated. PP is right, increase your protein and strength training. Increasing protein also increases satiety so you won't be hungry as often, nor will you crave fatty foods - the kind that are bad for you. For example eggs are a fatty food, but are also nutrient rich and an excellent source of protein, fat, and Vit D. In terms of strength training - I go 3 times a week and do a full body program, upper and lower. I'm not trying to win any contests just like 99.99% of the people you see in the gym. We're all just trying to stay healthy, strong, and yes physically attractive too.

Anonymous wrote:

Anonymous wrote:Personally I think the whole bulk and cut is crap. Just start strength training and increase protein.

This is OP and yes this sounds way too complicated for me. Is there a calorie and protein goal I should start with? How do I figure this out? And how frequently should I be heavy lifting?

PP here. Shoot for 100grams protein a day. It’s easy to hit if you eat chicken & white fish like haddock, hake, cod. Other low fat/high protein foods I eat are cottage cheese (low or non fat), plain Greek yogurt, jerky. I have a chocolate protein bar almost daily for “dessert” and it keeps me full through am workout.

Which brings me to lifting. I do Caroline Girvan programs. She’s free on YouTube and just launched an app. I would start with her Iron series. All straight lifting. The program is 5 x week but you can start with 3, then 4… just follow the program. Before you start and if you can afford, get a trainer to show you proper form. And don’t worry if you can’t lift even close to what she does. She’s professional. I started with 5lb for arms, 8 for legs. Some of he followers started with soup cans!

Lifting has changed my life. I’m almost 60 and love feeling strong.

If you are thin already as you are and that’s your basic body type, lifting isn’t going to bulk you up or make you “add fat”. For many women, you just get more of a toned hourglass shape.

Jut listen to your body. You’ll get hungrier with strength training, but if you eat decent food, as you probably already do, you’ll feel and look fantastic.

I’m bigger than you - 5’6”, 158. I was also a worried about bulking up from weightlifting and needing more calories all around. But what’s happened is that I’m exactly the same weight as before, but I look strong and toned and feel amazing in my body.

Anonymous wrote:

Anonymous wrote:Personally I think the whole bulk and cut is crap. Just start strength training and increase protein.

This is OP and yes this sounds way too complicated for me. Is there a calorie and protein goal I should start with? How do I figure this out? And how frequently should I be heavy lifting?

Its not that complicated. But you aren't going find an exact guide for your body and fitness goals in this forum. And then you have people like the above poster that assert that basic nutritional science is "crap" with no evidence posted otherwise and no expertise or qualifications to make such a claim. There are lots of online communities that have actual experts and you can get higher quality responses for your specific goals. Check out the FB groups Women Who Lift Weights, Bodybuilding for Women Over 40, and Macros Inc. If you're on reddit check out r/Bikinitalk (mostly about the bodybuilding sport & competitions but a lot of good general info too) and r/nutrition.

Anonymous wrote:Personally I think the whole bulk and cut is crap. Just start strength training and increase protein.

Well you're wrong.

Anonymous wrote:Personally I think the whole bulk and cut is crap. Just start strength training and increase protein.

This is OP and yes this sounds way too complicated for me. Is there a calorie and protein goal I should start with? How do I figure this out? And how frequently should I be heavy lifting?

Personally I think the whole bulk and cut is crap. Just start strength training and increase protein.

They say that for every pound of weight you gain, up to a third is fat (the rest muscle).

So it is just par for the course.

You go through a bulking stage -- gaining weight, mostly muscle, some fat, then a cutting stage of losing fat while trying to maintain the muscle you gained.

It's ongoing process that's never static.

Set some real goals -- weight, circumference of thighs whatever and then when you get there, see if you want to start cutting to lose fat.

such a great question - thank you for asking this!

Anonymous wrote:All muscle gain will come with some fat as well. To minimize it you want your calories coming from lean protein and nutrient dense foods and to be lifting as heavy as possible. If you’re new to working out and don’t have much muscle, you will be aiming for a recomp which is replacing fat with muscle, which means you may not see a difference in weight but you will in measurements and composition/appearance.

+1

You only need a small calorie surplus.

All muscle gain will come with some fat as well. To minimize it you want your calories coming from lean protein and nutrient dense foods and to be lifting as heavy as possible. If you’re new to working out and don’t have much muscle, you will be aiming for a recomp which is replacing fat with muscle, which means you may not see a difference in weight but you will in measurements and composition/appearance.

39, thin, want to gain some muscle mass. 5’5” 125 lbs

I am aware I need a calorie surplus and enough protein, but how should I eat and workout to balance gaining muscle and strength without just gaining fat? How much protein should I aim for daily? Looking for about a 5 lb muscle gain