Indeed, keeping a girl at a certain weight and proportions is not at all uncommon.
Here are a few quotes which speak to this matter.
The auctioneer took my hair in his hand and, cruelly, bent me back, standing. "22 horts," said he, indicating my breasts. "16 horts," said he, slapping me on the belly. "22 horts," said he, reaching across my body and placing his hand on my right hip, indicating the width of my body. These were my block measurements. I knew a master might keep me to such measurements, with the whip, if necessary.
Slave Girl of Gor    Book 11    Page 285
Peggy's body gleamed with sweat. She had small feet, and lovely, high arches. Her body was superb. She had retained, by means of diet and exercise, her block measurements, those measurements which were hers when she, after having been prepared for sale, was marketed from a slave block. The master commonly has a record of such measurements and many masters, using a tarsk scale, used for small livestock, and slave tapes, periodically check their lovely properties, making certain that they are maintaining the measurements. And woe to the girl, in such a case, whose measurements are found to depart to any significant extent from the block measurements! Such a departure can be an occasion for corrective discipline, and of a quite severe sort. Sometimes, when one sees a fearful girl refusing the smallest of sweets and exercising, almost in desperation, one may suspect, in amusement, that the day on which her master plans to check her measurements is not far distant. The lovely figures of slave girls are not accidents. Only free women are permitted to become unkempt and gross.
Guardsman of Gor    Book 16    Pages 263 - 264
I had been here only since yesterday morning. I then heard my height and weight, given in Gorean measurements, thirty and a quarter Gorean stone and fifty-one horts, or approximately, in Earth measurements, one hundred and twenty-one pounds and five foot three and three quarters inches, and a large number of my other measurements being similarly recounted. These would be my "block measurements," those which were mine as of now, on the date of my sale. Some masters will hold a girl to her block measurements, by the whip, if necessary. Others will insist on their improvement, under the penalties of a similar discipline, in one direction or another, depending on their own preferences. Other masters are quite lenient, or tolerant, at least within certain limits, pertaining to such measurements.
Dancer of Gor    Book 22    Pages 127 - 128
Indeed, the figures of both were nearly, if not quite, at what merchants in these matters refer to as the optimum block measurements for their size and weight. Block measurements, taken presale, are commonly, and in some cities this is required by law, included in a female's sales information. They are often available, as well, before the female is put on the block, hence the name 'block measurements'. Needless to say, too, given the female's subjection to severe regimens of rest, diet, and exercise, it is almost assured, as is desired, by attention to these "block measurements," that she will come to the block in excellent condition, healthy, vital, and well-curved. That is the way she is to be sold. She is, after all, merchandise, and, hopefully, good merchandise. Too, we may suppose, being healthy, each had the needs and desires of a healthy female, and, considering their selection, may have had these drives, and such, in an acute fashion, even uncomfortably so, which would render them particularly sexually vulnerable. Gorean slavers, for example, often pay close attention to such things. After all, most men buy women for pleasure.
Kur of Gor    Book 28    Pages 22 - 23
The female slave is expected to keep herself neat, well-groomed, clean, combed, brushed, and so forth. She is, after all, not a free woman. Too, she is usually expected to keep herself at her "block measurements," namely the measurements she was sold at. Accordingly, regimens of diet and exercise may be forced upon her.
Swordsmen of Gor    Book 29    Page 489
