Protein deficiency has been demonstrated to increase healing time. This has been noted in alcoholics who notoriously imbibe their nutrition by the bottle. Caloric deficiency in a mild state (dieting) has not been demonstrated to reduce healing time.
Pars and facet fractures tend not to heal. The best chance of healing is to avoid any significant motions of the lumbar spine. A flat back brace is what I use for patients with pars fractures but these braces won’t prevent deleterious motions, just remind patients to avoid the motions.
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.