Weight neutral approaches are experiencing a rapid growth period in research right now, although the foundational work began in the 1950s when intentional weight loss was first recognised as unlikely to be sustained, and social justice movements during the 1960's recognised clear discrimination against people with larger bodies.
These academic articles will get you started:
GENERAL OVERVIEWS OF SIZE ACCEPTANCE VS WEIGHT CENTRIC PERSPECTIVETylka, Tracy L., et al. "The weight-inclusive versus weight-normative approach to health: Evaluating the evidence for prioritizing well-being over weight loss." Journal of Obesity 2014 (2014).
O'Hara, Lily, and Jane Taylor. "Health at every size: A weight-neutral approach for empowerment, resilience and peace." International Journal of Social Work and Human Services Practice 2.6 (2014): 272-282.
SYSTEMATIC REVIEWS OF WEIGHT NEUTRAL INTERVENTIONSSchaefer, Julie T., and Amy B. Magnuson. "A review of interventions that promote eating by internal cues." Journal of the Academy of Nutrition and Dietetics 114.5 (2014): 734-760.