my daughter’s] weight.
Sherlock Holmes

A greater analysis of the situation provides a better picture. Let’s go back to the coffee shop before this all began and study the situation. Take a moment with me to put on our Sherlock Holmes’ hats and examine the evidence. First, there was no prior interaction between the tea lady and my daughter that would suggest a clash of egos was occurring. Second, the tea lady was wearing workout clothes which would suggest that she had some intent of exercise. Finally, the tea lady was drinking hot tea – not coffee – on a weekend morning. Without much effort at deduction, it was apparent that the tea lady was, herself, concerned about her own bodily appearance.
Starting with the assumption we have just made, let’s see how we can make sense of Rule 1 – Every action of a human being has a self interest. We can rule out that the tea lady was trying to derive satisfaction for her own self by debasing my daughter. Such value is generally only obtained by the message sender when they know the message receiver and can ascertain more self-value as compared to the other party. As previously indicated, this was a first-time meeting between the two parties with no history or interaction.
You are probably running away now with your own ideas of what the meaning was of the tea lady’s statement. It is a much more simplistic exercise as an impartial observer. Indeed, the information can be apparent to most everyone else besides ourselves when we are involved. The most likely truth behind the statement of the tea lady was that she was simply trying to talk herself out of such a delicious drink. The statement of the tea lady was about the tea lady and was intended to benefit the tea lady.
A normal argument might ensue between the two parties that resembles the following conversation.
Daughter - “Why did you call me fat?”
Tea Lady – “I did not call you fat.”