It seems commonplace now for our Instagram feeds to be littered with pictures of girls with toned stomachs and gym selfies next to dumbbells. There’s no doubt that “strong” has become the new “skinny” for women, but is it a positive shift towards a focus on health over looking like a runway model, or yet another unhealthy obsession with body image?

Accounts like Kayla Itsines has 3.9 million followers and Jen Selter 7.6 million, so enough of us are engaging. Searching hastags like #fitspo, #girlswholift or #girlswholiftarehotter, brings up all the bum, legs and abs shots of women in teeny tiny gym clothes.

And with celebrities getting in on the #strongnotskinny action too, and some social media accounts exclusively pumping out “fitspo” pics and clean eating food snaps, it’s all very socially acceptable, even celebrated, to document your every rep and show your results off online.

Back to the grind @thelomaxway @markzim88 #girlswholift 💪🏻

A video posted by Millie Mackintosh (@camillamackintosh) on

But while the likes of Millie Mackintosh and Chloe Madeley have trainers, ample time to spend sculpting their muscles to perfection and a bank balance that allows as many health food as they desire, most of us congratulate ourselves if we’ve managed a gentle jog once in a while and resisted the urge for a Five Guys. So isn’t a perfectly toned figure just another unattainable ideal for most women?

Personal trainer Justin Maguire, of FE Fitness says: “Anyone who models themselves on someone else – that’s a problem. Celebrities get in shape for a film role or because they need to look a certain way for their jobs, so yes that’s unattainable.

“Women are under a lot of pressure to look a certain way but I try to help people establish their norm. One person’s norm is another person’s extreme.”

Don’t look like this when you go to the gym? Neither do most women (Thinkstock)

Whatever you think of “fitspo” on social media, you can’t get away from the facts. Strength training and an increase in muscle mass has significant health benefits over cardio alone. It burns more calories, increases your resting metabolic rate, improves posture, looks after tendons and ligaments, promotes better flexibility and, as you get older, helps protect bone density.

“While running or step-up classes are good for short term, only doing that type of training doesn’t promote muscular contraction or red blood cell increase,” Maguire says.

Another advantage is that strength training isn’t just about weights, it includes things like push ups, squats, lunges and planks. So you don’t necessarily need to join an expensive gym to do it.

On the face of it, there’s something satisfyingly equal about a movement promoting women getting stronger. While the pressure to be skinny really only applies to women, strong is now something it’s OK for women to be too. It also moves away from being obsessed with weight, because of course muscle weighs more than fat.

Maguire also points out that the strength training community is inclusive and supportive too. CrossFit for example has enjoyed booming popularity over the last few years.

But somewhere between a quest to be fitter and stronger, and how much our lives are entangled in social media, there’s a murky area where streams of photos documenting progress and results lie. Doesn’t posting pics and following others who do the same make it all the more addictive and scrutinising?

Plus, posting constant photos of your rippling abs and toned bum is a tad narcissistic, even if it is tied into health and fitness.

Psychology of eating expert Hala El-Shafie says the “gratuitous” images of toned stomachs is not only unnecessary but potentially dangerous.

“If you ask 100 women how they feel when they look at a photo like that more will feel inadequate than inspired. What if a girl exercises three times a week but doesn’t have abs like that? It could make her want to give up, or it could push her into something more extreme she’s not ready for.

“I hate the word ‘fitspo’ – for me it’s just like ‘thinspo’.”

She thinks there is a worrying comparison between the type of poses in pictures the #strongnotskinny hashtag attracts, and stomach photos on pro-anorexia sites.

“This was how pro-ana sites started. When I see a picture of a girl’s ab photo it reminds me of pro-ana poses. I feel really uncomfortable about it. If someone posts a photo to that hashtag or #fitspo it’s saying, ‘this is how you should look to be in our gang’.

“And people who are attracted to those hastags are likely to already be quite fixated on body image. That’s why it’s uncomfortable and potentially dangerous.”

There’s also the issue that most of us don’t look like Nike models or like we’ve just stepped out of the hair salon during a workout.

And, in the same way that our social media accounts are an edited “perfect” version of our much more complicated lives, when gym fanatics upload their latest rippling abs pic they probably forgot to mention that pain of the last 10 reps or how they debated over whether or not to eat a biscuit for an hour. Basically, they make it look easy, and let’s face it, glamorous.

Fitspo accounts only promote one type of strong, one body type, and while it may not be skin and bones, it’s still slim. Even if you live a very healthy lifestyle, most people have quite different natural body types. Serena Williams for example, is strong, but her body is still cruelly scrutinised and criticised.

Charlie Merton is a yoga teacher but promotes a different kind of strong.

“Strength isn’t just about what your physique looks like. It’s about being agile too, it’s about being able to carry your own bodyweight, not just muscle definition – which is really just a result of a lack of fat on the body.

“I’m a size 14, some parts of my body are a 16, some a 12. Looking at me, you wouldn’t see the usual media image of a ‘yoga body’. I’m not ripped but I’ve got a lot of strength, I can hold my own bodyweight, I can do a headstand.

“I used to have a lot of issues with how I look, I’d get all dressed up for a night out then feel too fat to go. Yoga has helped me accept who I am.”

She adds: “I think posting pictures at the gym takes away from the focus of why you’re there in the first place, you’re there to work out, to sweat, not to look attractive.”

And what about when next to all those pictures of strong bodies there are posts of gym devotees’ raw courgettes and green juice.

Maguire says: “I think deciding to post all your meals online is a great way to restore a sense of health. It makes you more mindful of what you eat. It also creates a bit of healthy competition and gives people new culinary ideas.”

But El-Shafie, who runs Nutrition Rocks, says it can fall very quickly into otherexia – healthy eating to the point where it becomes obsession.

“Working on your health and fitness is great but you need to ask how much of your life it takes up. If all you’re doing is thinking about food, exercising and scrolling through ab photos on Instagram thinking ‘I wish I looked like that’ there’s a problem.”

While many of us could probably do with being healthier and yes, stronger, we need to be careful movements like this don’t put women’s bodies under even more scrutiny.