Purpose: Dutch Health care professionals (HCPs) provide little information concerning health risks associated with weight gain during chemotherapy for breast cancer. Women with breast cancer have specified the need for more information on nutrition and physical activity to deal with weight gain. The aims of this study were to assess the perceptions of Dutch HCPs on weight gain during chemotherapy and in addition evaluate whether and what kind of information on dietary intake and physical activity HCPs provide to prevent/treat weight gain during (neo)adjuvant chemotherapy. Methods: A qualitative study was conducted using semi-structured interviews with 34 HCPs involved in breast cancer care: general practitioners, oncologists, specialized nurses, and dieticians. Results: To date, little information about nutrition, physical activity, and weight gain is given during chemotherapy because it is not part of most HCPs’ training, it is not included in the guidelines and it is not the best time to bring up information in the opinion of HCPs. Weight gain was perceived as just a matter of a few kilos and not an important health issue during treatment. All HCPs felt it is better that women themselves addressed their weight gain after chemotherapy. Conclusion: More knowledge about health risks associated with chemotherapy-induced weight gain and how to combat these issues needs to be made readily available to the HCPs and should become part of their training. Existing patient guidelines should include information on how to prevent and/or reduce weight gain through self-management of nutrition intake and physical activity during and post chemotherapy.