Hey Aleysus,
15kg weight loss is very impressive and I hope youโre feeling better for it!
I am by no means an expert but i have quite a lot of experience with nutrition and health and weight loss so iโll just give you my thoughts on what i think the weight loss could be caused by. sorry this may be quite a long post as well.
If we break down the weight loss over the 8 months, youโve lost around 2kg a month which equates to roughly 1lb a week. This is a 500 calorie deficit under your maintenance calories per day for the 8 months (3500 calorie deficit under your maintenance = roughly 1lb of fat). So if youโre in a 3500 calorie deficit over the week youโd lose around 1lb per week. This may well be the case if youโve swapped out sugary drinks for diet drinks, or increased your exercise, or cut out a few snacks, or maybe a combo of all, you could quite easily put yourself in a calorie deficit without realising. It could also be a case of losing water weight which can fluctuate depending on what you eat and if youโre eating more or a case of losing muscle if youโre someone who would gym regularly and then stopped, youโll start losing your muscle youโve gained and therefore also lose weight.
Unexpected weight loss could also be caused by a number of other factors outside of your diet. for example, in times of stress, like losing a job, loss of a loved, the ending of a relationship, those kind of things can have an impact on your mental health which can cause weight loss. it could also be a digestive issue, such as ibs or maybe a new gluten intolerance which has caused coeliac disease, that would also cause weight loss. also if you had started a new course of medication, this can impact your weight too, so thatโs something to factor in as well. other health conditions to maybe research would an overactive thyroid - which controls your metabolism so when itโs overactive your metabolism increases and youโll lose weight eating the same number of calories as before. type 2 diabetes is also something would cause weight loss. and i donโt mean to scare you at all with this, unexpected weight loss is also a symptom of cancer but this is ofc in rare circumstances but something to be aware of.
I guess the big thing would be to monitor your energy levels, and maybe try counting your calories if you are concerned about the weight loss and maybe a trip to the gp to have a chat about it and get a more expert opinion on the matter. Also, sudden weight loss due to any serious health condition generally happens in people over 60 or 65 i canโt remember exactly which one it is, so age is also a factor to think about in this too.
Sorry for the long response and i apologise if iโve worried you at all, thatโs not my intentions whatsoever, just trying to give as much info as i can. But if youโre feeling good and healthy, thereโs probably nothing at all to worry about and i congratulate you on your weight loss ๐
Also if youโd like any more info or would like a chat about anything in more depth feel free to send me a message and iโll be happy to try help.