Personal trainer who struggled with body image reveals natural way women's bodies change throughout menstrual cycle

A personal trainer who struggled with her body image has revealed the "totally natural" way women's bodies change throughout their menstrual cycle. Sia Cooper, 33, became a personal trainer after losing 45lb she put on while working as a nurse. The mum-of-two admits she was "obsessed" - but now loves her body as it is, and says "if I want pizza I’ll have some". As part of her mission to embrace "total body positivity" she filmed a video showing how her perfectly healthy body changed during her menstrual and hormonal cycle. In the video, with footage taken throughout January, Sia shared on the caption: "Watch me grow! "Hormones can make us feel not so pretty sometimes. But it's ok! Even though PMS symptoms aren't so pleasant and we feel our least best, it's important to remember that you're not alone." Sia, from Destin, Florida, said she was inundated with positive comments when she posted it on her social media platforms. She said: "My mission was to tell women 'you’re not the only one feeling crappy and bloated', because our bodies fluctuate naturally throughout the month. "The week after our period we could weigh 120lb, and the week before we could weigh 125lb. "It’s not your fault, and you can't totally control this process. "These are changes all women experience in their monthly cycle. "Each week there are little changes that go on. For example before your period you do tend to bloat because your body tends to retain more water to prepare for your period. "It’s your body’s normal mechanism to protect your body." Sia said she wants to share "total body positivity" with women through her social media platforms. "The message behind this is total body positivity," she said. "Lots of women tell me 'I feel heard and I feel better'. "Sometimes there is an issue but most of the cases you are normal - it's normal for your body to change. "I gained 30lb during my first pregnancy and after I just thought 'this doesn’t matter'. "I have a daughter and I don’t want her to grow up thinking she has a problem because she has a dimple on her thigh. "Just remember that you’re human, there is nothing wrong with you, and you’re normal." Sia said as a child she suffered with bulimia. As an adult she was the "heaviest she had ever been" at 150lb, after graduating in 2010. She smoked two cigarettes a day and ate Burger King several times a week, and decided to lose weight because she "hated" the way clothes fit on her. "I was a nurse and I was the heaviest I had ever weighed because it was super stressful just after graduation," she said. "I lost 45lb in a year. "Now I’m more relaxed, as when I first lost weight I kind of became obsessed with it. "I was 105lb at one point, and I thought I was being very positive about foods, but now I’m all about balance. "If I want pizza I’ll have some, just not the whole box. If I want cookies I'll have one or two, not the whole packet. "I lost weight through calorie restriction and by eating more organic foods. "It was pretty plain and simple - I cut out fast food and sugar. "It was mainly just dietary changes as I was already active by doing eight hour shifts in the hospital five days a week." "It’s been a journey coming to accept my body. "Growing up I struggled with bulimia, because my mother made fun of my weight. "Then as an adult I didn't look after my health. Sia said becoming a mother helped to improve her relationship with her body. "It wasn’t until I had my first baby, my son Grayson, that I started appreciating my body for what it is and not just the number in the scale," she said. "What is really important to remember is that your weight doesn’t give a full picture of health. "What will help you to understand your wellbeing is going to the doctor and getting blood diagnostics. "If you do want measurements, I would suggest you go ahead and start measuring yourself with the measuring tape. "That will give a much more accurate picture." Mother to Grayson, nine, and Everly, six, she qualified as a personal trainer in 2015 and now works in fitness full time using her platform "Diary of a Fit Mommy".