Table 2.

Association of various factors and estimating BMI beyond or within ±1.40 kg/m².

Self-reported BMI:	Under-Estimated		Correctly Estimated		Over-Estimated
BMID (self-reported - measured):	< -1.40 kg/m2		Within ±1.40 kg/m2		> 1.40 kg/m2
	N = 852 (43.8%)		N = 1000 (51.4%)		N = 93 (4.8%)
	N	%	N	%	N	%	P value
BMI Category §
Underweight	0	0.0	13	1.3	2	2.2
Normal Weight	153	18.0	490	49.0	48	51.6
Overweight	371	43.5	363	36.3	31	33.3
Obese, Class I	233	27.3	107	10.7	8	8.6
Obese, Class II	75	8.8	21	2.1	2	2.2
Obese, Class III	20	2.3	6	0.6	2	2.2	< 0.001
Sex
Male	366	43.0	449	44.9	47	43.0
Female	486	57.0	551	55.1	46	57.0	0.327
Age
18-29 y	90	10.6	184	18.4	16	17.2
30-44 y	202	23.7	329	32.9	34	36.6
45-64 y	331	38.8	366	36.6	29	31.2
65+ y	229	26.9	121	12.1	14	15.1	< 0.001
Social class §§
SC 1-2	334	37.6	382	39.8	26	26.8
SC 3-4	366	41.2	372	38.8	40	41.2
SC 5-6	119	13.4	134	14.0	20	20.6
Unclassified	70	7.9	71	7.4	11	11.3	0.134
Current smoking status
Former smoker	238	27.9	227	22.7	15	16.1
Non-smoker	431	50.6	479	47.9	43	46.2
Smoker	183	21.5	294	29.4	35	37.6	< 0.001
Alcohol consumption
Never	183	21.6	137	13.7	23	25.0
Monthly or less	145	17.1	150	15.0	25	27.2
3-4 times/month	198	23.3	268	26.8	19	20.7
2-3 times/week	235	27.7	338	33.8	18	19.6
4 or more times/week	88	10.4	107	10.7	7	7.6	< 0.001
Marital status
Single (never married)	185	21.8	244	24.5	28	30.1
Married/Cohabiting	538	63.3	641	64.3	53	57.0
Divorced/Separated/Widowed	127	14.9	112	11.2	12	12.9	0.066
Education
Some/Completed Primary School	138	16.2	113	11.3	18	19.4
Some/Completed Secondary School	387	45.4	423	42.3	48	51.6
Diploma/Certificate	156	18.3	222	22.2	11	11.8
Bachelors/Postgraduate Degree	171	20.1	242	24.2	16	17.2	0.001
Ethnicity
White	826	98.2	971	97.9	90	96.8
Black	5	0.6	4	0.4	1	1.1
Asian	3	0.4	8	0.8	2	2.2
Other	7	0.8	9	0.9	0	0.0	0.392
Physical Activity
High IPAQ Score	221	25.9	214	21.4	25	26.9
Medium IPAQ Score	425	49.9	514	51.4	47	50.5
Low IPAQ Score	206	24.2	272	27.2	21	22.6	0.156
Self-described weight §§§
About the right weight	419	49.6	607	60.8	48	51.6
Too heavy	377	44.6	324	32.5	35	37.6
Too light	22	2.6	42	4.2	3	3.2
Not sure	27	3.2	25	2.5	7	7.5	<0.001
Attempting to manage weight
No	406	47.7	540	54.0	49	52.7
Lose weight	320	37.6	294	29.4	32	34.4
Maintain weight	118	13.8	157	15.7	12	12.9
Gain weight	8	0.9	9	0.9	0	0.0	0.020

BMI, body mass index; SC, social class; IPAQ, International Physical Activity Questionnaire.

§ BMI categories defined as: Underweight (<18.5 kg/m²), Normal Range (18.5-24.9 kg/m²), Overweight (25.0-29.9 kg/m²), Class I Obese (30.0-34.9 kg/m²), Class II Obese (35.0-39.9 kg/m2), and Class III Obese (40.0 + kg/m2).

§§ Household social class defined according occupation type, as per methods in ref. [23].

§§§ Self-described weight taking into account one's age and height.

All comparisons were made using Pearson chi-squared tests.