I am not sure how you reassure them. Have you had an eating disorder in the past? You say you are in the healthy range NOW and that your goal is to lose more weight for "vanity" - is your goal weight still in the healthy range? Is there any reason why they might have to be legitimately concerned? Are you eating enough to be HEALTHY? I suppose it is the mother in me that has to ask these questions - not all weight loss is healthy - and if someone cares enough about you to question it, you might want to answer these questions for yourself and then you will be in a better position to KNOW what to tell them. Seeing that you are in the range of 100-110 pounds, depending on your height, body build, and such, there COULD be a reason for concern. If you were 200 and they were getting antsy about you losing too much, my answer would be a little different. I am not about to judge YOUR weight or your journey, but as a mother, I would suggest that you at least ask yourself whether they have any reason for their concern. If not, simply explain that this is a healthy eating plan and a lifestyle change and NOT A DIET. If there is cause for concern, then take the steps you need to make sure it IS A HEALTHY LIFESTYLE CHANGE and you WILL reassure them.