On a morning last year, I logged onto my teenage daughter's student profile to add lunch money to her account.
I was surprised to find only a few dollars missing.
We were driving when I confronted her. I could tell she was having difficulty putting her thoughts into words.
"Mum," she blurted out, "I want to lose weight."
I pulled over into a parking lot.
She confessed that during gym class, all the girls had to line up and have their weight and body mass index measured. Afterwards, several started a diet soda weight-loss plan.
My daughter - an average-size teenager - had been buying only a diet soda each day. She had not eaten lunch in a week.
My daughter and I are tight, so my first question was: "Why didn't you discuss this with me?"
But I knew the answer: The body positivity movement had hit our relationship.
I am a fat woman. I was a fat teenager. It took me years of hard work to learn to accept myself, but I finally embraced the idea that my body was healthy at any size.
However, the past few weeks had cast those beliefs into doubt.
One morning, I awoke with a small bruise on my thigh. A few days later, I was in the hospital.
I had been bitten by a brown recluse spider and had a flesh-eating streptococcus infection.
I also had a completely unrelated diagnosis: type 2 diabetes, and it was progressing quickly.
Connected to a vancomycin drip, I argued with my doctor. "How can I have type 2 diabetes? I eat fruit and vegetables. I walk, I do Pilates.
"You can be healthy at any size, you know."
"Look at where you are," he snapped. "You're not healthy at any size. Unless you make some major changes, you've probably got about 10 years left to live."
I was 41 years old.
Around the same time, advance copies of my debut young adult novel were making their way out into the world. Because I had wanted to examine the toll of fatphobia, I wrote it in two timelines, following the same character, before and after a major weight loss.
The point was to tell teenagers that they were worthy of pursuing their dreams.
But some readers just did not think it was okay to show a teenager, or anyone really, losing weight.
Many people in the body positivity movement - which I would like to count myself a member of - believe that the desire to lose weight is never legitimate because it is an expression of the psychological toll of fat shaming.
So any public discussion of personal health or body size constitutes fat shaming.
This recently prompted the founder of Greatist, a health and fitness site, to defensively write, "It's okay to want to lose weight", in response to criticism.
It is worth noting that body positivity is the convergence of a few movements.
The fat acceptance movement was pioneered in the 1960s by black women to fight discrimination in public spaces, the workplace and doctors' offices.
Fat positivity, more of a reaction to fat shaming, and body positivity, a more commercial self-esteem movement, came later.
The problem with today's version of body positivity is that it refuses to acknowledge that no one approach is right for every scenario.
One teenager might grow up to be healthy at any weight and another might end up in the hospital.
It left my own daughter afraid to approach me about a topic on which I have both personal experience and expertise. It left me feeling like I could not voice the rational concerns I have about diabetes.
I was the "wrong" kind of body positive because I had been forced to admit that there could be serious health consequences to fatness.
I was the wrong kind of mother because I felt I had to be supportive of my daughter's weight-loss goals instead of talking her out of them.
And I was the wrong kind of writer because I wanted to explore all aspects of this topic instead of telling fat girls that every problem can be resolved by learning to love themselves.
Shutting down the conversation will not help. It will only leave girls alone at the proverbial lunch table in a culture that sends confusing messages about dieting, body image and health.
For me and my daughter, the solution has been to talk - even if it is awkward or painful.
She did not want to grow up to weigh 136kg like me. I do not want that either.
But we also talked about self-esteem and self-love. About health and the predatory nature of the diet culture.
We put a stop to the meal skipping. She chose some healthier foods, started playing a sport and is having discussions with a counsellor.
In my case, I am still trying to get it right. But I have come to feel that loving yourself and desiring to change yourself are two sentiments that should be able to peacefully co-exist.
• Kelly deVos is the author of Fat Girl On A Plane.