On 2018 Jan 29, John-Olov Jansson commented:

Response to Klaus: We thank Dr Klaus for her useful comment regarding possible sex differences in the response to increased loading. We have consistently found the effect of increased loading to be similar in female and male mice on high fat diet. However, we have not evaluated possible sex differences in the response to increased loading in non-obese rodents given standard diet. One possible explanation for previous inconsistent results could be that the effect of loading in these studies was not evaluated in obese mice on high fat diet, an often used model for clinical obesity.

On 2018 Jan 23, Susanne Klaus commented:

I would like to comment on two points. (i) I feel that the discussion would have profited from comparing this study to previous studies using the same experimental approach, i.e. weight implantation to investigate the role of weight per se in body weight regulation (1-3). (ii) Since our previous study using the same experimental approach showed considerable sex differences in the reaction of mice to an implanted weight load it is unfortunate that in all except one experiment the sex of the animals used was not indicated and the question of possible sex differences not even mentioned. This makes it very hard to relate the presented data to previous investigations regarding the existence of a ponderostat (here termed “gravitostat”). In our study published in 2004 (1) we implanted weight loads both into male and female FVB mice resulting in drastical sex difference in long term body weight regulation observed over a period of 14 weeks. While male mice showed a partial long term compensatory decrease in body weight due to decrease of fat mass in response to an increased weight load, female mice regained biological body mass within 3 to 4 weeks after the initial weight loss due to surgery. Furthermore, contrary to males, female mice did not reduce food intake and body fat in response to an implanted weight load in the long term. These gender-specific differences in body mass regulation point to different strategies in males and females to cope with a situation affecting body mass and energy demands suggesting a higher efficiency of energy conservation in female compared to male mice.

1. Wiedmer P, Boschmann M, & Klaus S (2004) Gender dimorphism of body mass perception and regulation in mice. J Exp Biol 207(Pt 16):2859-2866.
2. Adams CS, Korytko AI, & Blank JL (2001) A novel mechanism of body mass regulation. J Exp Biol 204(Pt 10):1729-1734.
3. Wiedmer P, Boschmann M, & Klaus S (2002) Weight per se influences body mass regulation differently in male and female mice. J Gravit Physiol 9(1):P189-190.

On 2018 Jan 23, Susanne Klaus commented:

I would like to comment on two points. (i) I feel that the discussion would have profited from comparing this study to previous studies using the same experimental approach, i.e. weight implantation to investigate the role of weight per se in body weight regulation (1-3). (ii) Since our previous study using the same experimental approach showed considerable sex differences in the reaction of mice to an implanted weight load it is unfortunate that in all except one experiment the sex of the animals used was not indicated and the question of possible sex differences not even mentioned. This makes it very hard to relate the presented data to previous investigations regarding the existence of a ponderostat (here termed “gravitostat”). In our study published in 2004 (1) we implanted weight loads both into male and female FVB mice resulting in drastical sex difference in long term body weight regulation observed over a period of 14 weeks. While male mice showed a partial long term compensatory decrease in body weight due to decrease of fat mass in response to an increased weight load, female mice regained biological body mass within 3 to 4 weeks after the initial weight loss due to surgery. Furthermore, contrary to males, female mice did not reduce food intake and body fat in response to an implanted weight load in the long term. These gender-specific differences in body mass regulation point to different strategies in males and females to cope with a situation affecting body mass and energy demands suggesting a higher efficiency of energy conservation in female compared to male mice.

1. Wiedmer P, Boschmann M, & Klaus S (2004) Gender dimorphism of body mass perception and regulation in mice. J Exp Biol 207(Pt 16):2859-2866.
2. Adams CS, Korytko AI, & Blank JL (2001) A novel mechanism of body mass regulation. J Exp Biol 204(Pt 10):1729-1734.
3. Wiedmer P, Boschmann M, & Klaus S (2002) Weight per se influences body mass regulation differently in male and female mice. J Gravit Physiol 9(1):P189-190.

On 2018 Jan 29, John-Olov Jansson commented:

Response to Klaus: We thank Dr Klaus for her useful comment regarding possible sex differences in the response to increased loading. We have consistently found the effect of increased loading to be similar in female and male mice on high fat diet. However, we have not evaluated possible sex differences in the response to increased loading in non-obese rodents given standard diet. One possible explanation for previous inconsistent results could be that the effect of loading in these studies was not evaluated in obese mice on high fat diet, an often used model for clinical obesity.