Waist-to-height ratio can help supplement the BMI measure without needing any special body fat scales or stuff like that.
It’s also a really simple one to remember. Keep your waist circumference below half your height.

Our aim was to differentiate the screening potential of waist-to-height ratio (WHtR) and waist circumference (WC) for adult cardiometabolic risk in people of different nationalities and to compare both with body mass index (BMI).
[…]
Compared with BMI, WC improved discrimination of adverse outcomes by 3% (P < 0.05) and WHtR improved discrimination by 4-5% over BMI (P < 0.01). Most importantly, statistical analysis of the within-study difference in AUC showed WHtR to be significantly better than WC for diabetes, hypertension, CVD and all outcomes (P < 0.005) in men and women. For the first time, robust statistical evidence from studies involving more than 300 000 adults in several ethnic groups, shows the superiority of WHtR over WC and BMI for detecting cardiometabolic risk factors in both sexes.

• https://www.researchgate.net/publication/51820603_Waist-to-height_ratio_is_a_better_screening_tool_than_waist_circumference_and_BMI_for_adult_cardiometabolic_risk_factors_Systematic_review_and_meta-analysis
  November 2011
  Obesity Reviews 13(3):275-86
  DOI:10.1111/j.1467-789X.2011.00952.x
  Source - PubMed