Tonight the internet is abuzz over something called a dad bod. What is a dad bod? It is not fat, not thin, it's just right according to the college women that catapulted the term to viral status. As a... See More
Tonight the internet is abuzz over something called a dad bod. What is a dad bod? It is not fat, not thin, it's just right according to the college women that catapulted the term to viral status. As a 40 something-year-old dad, I find this notion profoundly reassuring. However, not everybody is pleased. Here tonight is ABC's Mara schiavocampo. Reporter: Introducing the new "It" body type for bros. Who needs wash board abs and bulging bye accepts apparently what some women want is a soft, doughy dad bod. It is a healthy meet yum between heavier set and worksout. The average guy body. My friends and I saw this body type on more guys and we were attracted to it. Reporter: Dad bod inspiration, think Jason Siegel's nude scene in "Forgetting stair Sara Marshall" or Paul rudd downing cupcakes in this is 40. It was this article why girls love the dad bod written by Mckenzie Pearson that made dad bod an internet sensation. She says this is why. It makes girls I think feel more vulnerable when they aren't with someone who is meal prepping every Sunday and being intimidating. The experience of cuddling with someone who has a little more on them than pure muscle and bone and skin is definitely more comforting. Reporter: Mega stars like Leonardo Dicaprio and Seth rogen have been called dad bods so for Zach Rosenberg he's in good company. You are working with a lack of muscle deaf nation across your chest and abs which I definitely have. I have abs in there someone. Young I don't know how many there are but at least two. Let me see yours. Reporter: Shortly after Mckenzie's dad proclamation went viral there was a tidal wave of controversy. Men were rejoicing. Women started to cry foul on Twitter using the #mombod. Would a woman ever be celebrated for flaunting a mom bod? The fact of the matter is the dad bod is the average body. Most people can't live in a G.I. Most people don't have six pack abs. It's what average guys look like. In a way it's great they can be made to feel good about that. But what about the women on the oh side of that? The double standard annoys women to no end. When I saw the dad bod piece, I thought no one talks about mom bods like this. No one is writing cute lists of top ten reasons you would want to date someone with a mom bod. It is because mom bod is real but seen as a negative. Reporter: Sara is a blogger and mother of two twin girls based out of Little Rock. When she heard of dad bod she immediately wrote a post about being proud of her mom bod. Mom bod is something you need to get rid of as soon as having a baby because if there is any evidence on your body that you have had a baby it's a problem. A mom bod doesn't have six-pack abs. A mom bod has softness it to. It has been through the wringer a bit. Probably tired. Mom bod would probably rather wear stretchy pants, but mom bod is strong and mom bod is soft. Reporter: The pressure to be a hot mom can be overwheming with some women sharing their trim post-baby bodies all over social media. Take lingerie model stair Ra stage for example. She stirred up controversy by posting these pictures of herself nine months pregnant with six-pack abs. Critics called her too fit to be pregnant. I'm just doing me. I did this before I was pregnant. I want to do this after. I don't feel like I should have anything to hide and be ashamed of. I'm so excited. I'm so happy. So why not share it with everybody? Reporter: Now she's had the baby and bounced back immediately, sharing these snaps with her fan following shortly after giving birth. She maybe an extreme example but nonmoms can feel the pressure too. One reason that Sara thinks it is time we all embraced the mom bod. I think mom bod pride should be a movement because everybody should be able to be proud of who they are in the skin they are in. They are the ones that make you sexy. Your body doesn't decide whether you are sexy. I think every mother on the face of the Earth would love if the world embraced the mom bod, the flabby body and stop the pressure we all feel to be thin an perfect and beautiful all the time. Reporter: Over 41% of men over 18 in the U.S. Are overweight. So embracing the dad bod could be a convenient way to accept the bodies many men already have. I think that dad bods are, you know, sexy because as the original article stated it's kind of a non-intimidating body type. Who has a bigger muscle, me or you? Me. I think celebrating a body type that has more to love is totally a realistic way to go. Reporter: Rosenberg found the dad bod trend so amusing, he created a fake diet plan to help his fellow dads get the perfect flabby body. Part of the 30 day dad bod challenge if you want to participate. We have awesome stuff like pizza, cake and tacos. Pizza's here. It's a funny joke we are enjoying now and dads are saying, great we have an excuse not to do sit ups tonight. Reporter: He said embracing a little flab might be good for everyone. I hope the mom bod becomes a thing. Moms should feel comfortable in their skin. Good thing it is cheat day celebrate their husband's dad bods and dads should be celebrating their wives' mom bods and we can all be happy and healthy together and a little squishy. Reporter: For "Nightline," I'm Mara schiavocampo in new York. Our thanks to Mara schiavocampo. Tonight what do you think of the concept of dad bods head to our Facebook page and let us know.
This transcript has been automatically generated and may not be 100% accurate.