2023 Volume 1 Issue 2 Pages 26-33
Aim: To determine the lifestyle characteristics associated with obesity among adult citizens living in Yugawara town, Kanagawa Prefecture, Japan.
Methods: We conducted a cross-sectional study consisting of a survey using a “Daily Living Conditions questionnaire.” The study participants were 397 subjects aged 40–64 years from Yugawara town, Japan. For data analysis, participants were divided into two groups according to body mass index (BMI) as follows: normal weight group (BMI: 18.5–24.9 kg/m2) and overweight/obese subjects group (BMI ≥25.0 kg/m2). The outcome variable was obesity, while the questionnaire items, including drinking and eating patterns, were the explanatory variables. Logistic regression analysis was performed to assess the association between obesity and lifestyle-related explanatory variables.
Results: Obesity was associated with “eating dinner alone” (odds ratio [OR] = 2.10; p = 0.009, 95% confidence interval [CI] = 1.20–3.70), “small family size” (OR = 2.87; p = 0.003, 95% CI = 1.43–5.78), “eating very fast” (OR = 1.74; p = 0.038, 95% CI = 1.03–2.93) and “abstaining from or infrequently drinking alcohol” (OR = 2.22; p = 0.006, 95% CI = 1.26–3.90). Furthermore, “daily alcohol consumption” (OR = 0.37, p = 0.004; 95% CI = 0.18–0.73) was associated with lower obesity risk.
Conclusion: This study’s findings show that eating alone may lead to nutritional imbalances among Japanese citizens living in Yugawara town, highlighting the importance of promoting a well-balanced diet.
The prevalence of obesity (body mass index [BMI] ≥25 kg/m2) among adults in Japan is reported to be 33% in men and 22% in women1), and this rate has been trending upwards in recent years1). Several factors have contributed to this rise, including a sharp increase in the intake of animal protein and fats—elements not frequently consumed in the traditional diet due to the Westernization of dietary habits2–4). Living alone, which is often associated with a nutritionally imbalanced diet, is also a contributing factor5). Notably, among adult men aged 65 and older, regardless of whether or not they live with family members, eating meals alone stands out as a primary contributor to obesity6).
Previous studies have pointed out that unhealthy eating habits, such as overeating, skipping breakfast, and a preference for fried foods, can lead to obesity7,8). Additionally, the speed at which one eats can contribute to being overweight for various reasons9–14). Hence, it is crucial to eat slowly and mindfully, allowing the body time to send the necessary satiety signals to the brain, which can help prevent overeating. Consuming balanced meals with the proper nutrients, drinking enough water, and exercising regularly can help maintain a healthy weight.
Many studies have demonstrated a positive association between alcohol consumption and obesity15,16), and high alcohol consumption is commonly perceived by the Japanese to lead to obesity. Alcohol, being high in calories17), can raise blood sugar levels and stimulate appetite18), thereby reducing motivation for physical activity19). However, evidence regarding the relationship between alcohol consumption and obesity is inconsistent and inconclusive. While one cohort study reported an association between alcohol consumption and a reduced risk of obesity in women20), another found no correlation between being overweight and consuming alcohol21).
Thus, the relationship between obesity and alcohol consumption is multifaceted and closely intertwined with dietary and drinking habits. This study seeks to explore the correlation between obesity and various factors using a comprehensive survey conducted among middle-aged residents of Yugawara, Kanagawa Prefecture.
The questionnaire was part of a survey that informed the creation of a health- and dietary education-promotion plan for Yugawara town in Kanagawa Prefecture. The survey targeted men and women of working age, defined as 40–64 years, in Yugawara town, and it was conducted from February to March 2015. The questionnaire was self-administered and mailed. Of the 1,120 questionnaires delivered, 442 were returned, resulting in a response rate of 39.5%. The remaining 678 were not returned.
Survey itemsThe question items of the Yugawara Town Health Survey were stratified into the following items. The question categories included 31 questions regarding BMI, demographics, nutrition, exercise, mental health, tobacco, alcohol, and dental information. Those with blanks in any of the height and weight categories were removed, and the analysis was conducted with 430 respondents. If an answer was left blank, it was treated as a missing value. The questionnaires are shown in Supplementary Data 1.
Study groupsFig. 1 shows the analytical flowchart of this study. BMI was calculated as body weight (kg) divided by height (m2). Participants with a BMI greater than 18.5 kg/m2 were selected (n = 397) and then divided into two groups. Participants with a BMI between 18.5 and 24.9 were considered the normal weight group (n = 313), and those with a BMI of 25.0 or higher were considered the overweight/obese subjects group (n = 84).
Student’s t-test was used to compare the differences in the average values of age, height, and body weight by obesity class. Categorical variables were analyzed using Fisher’s test and are presented as n (%). Binary logistic regression was performed with overweight as the dependent variable (BMI ≥25), and “age” and “sex” as adjustment factors. EZR version 1.61 was employed as the analysis software22). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated, and the p value was <0.05.
Table 1 delineates the characteristics of the participants in this study. Among the 396 participants categorized by weight, in terms of sex distribution, 43.6% (136) of men were of normal weight, compared to 56.4% (176) of women. Conversely, 51.2% (43) of men and 48.8% (41) of women were categorized as overweight or obese. This difference in weight distribution by sex was not statistically significant, as evidenced by a p value of 0.220.
| Variable (n) | Normal weight (%) | Overweight/obese (%) | p-value | |
|---|---|---|---|---|
| Sex (396) | Men | 136 (43.6) | 43 (51.2) | 0.220b |
| Women | 176 (56.4) | 41 (48.8) | ||
| Age (years) (354) | Mean (SD) | 54.4 (7.3) | 53.8 (7.2) | 0.362a |
| Height (cm) (397) | Mean (SD) | 162.5 (8.6) | 163.1 (8.7) | 0.732a |
| Body Weight (kg) (397) | Mean (SD) | 61.2 (10.8) | 69.7 (11.7) | >0.001a |
| Family structure (387) | Living alone | 29 (9.3) | 18 (21.4) | 0.003b |
| Married life | 277 (90.7) | 63 (78.6) | ||
| Breakfast Companions (345) | The family | 64 (23.7) | 13 (17.3) | 0.179b |
| Not all together, but eating with the family | 81 (30.0) | 21 (28.0) | ||
| Alone | 106 (39.3) | 28 (37.3) | ||
| Alone (because I live alone) | 19 (7.0) | 13 (17.3) | ||
| Dinner Companions (392) | The family | 147 (47.6) | 35 (42.2) | 0.010b |
| Not all together, but eating with the family | 97 (31.4) | 18 (21.7) | ||
| Alone | 40 (12.9) | 13 (15.7) | ||
| Alone (because I live alone) | 23 (7.4) | 17 (20.5) | ||
| No | 2 (0.6 | 0 (0.0) | ||
| Eating Speed (393) | Very slow | 5 (1.6) | 1 (1.2) | 0.038b |
| Slightly slow | 25 (8.1) | 4 (4.8) | ||
| Normal speed | 134 (43.2) | 29 (34.9) | ||
| Slightly fast | 101 (32.6) | 31 (37.3) | ||
| Very fast | 45 (14.5) | 18 (21.7) | ||
| Alcohol Consumption Frequency (390) |
Every day | 103 (33.4) | 17 (20.7) | 0.006b |
| ≥3 days/week | 38 (12.3) | 7 (8.5) | ||
| 1 day/week | 34 (11.0) | 11 (13.4) | ||
| Hardly drink | 48 (15.6) | 16 (19.5) | ||
| Formerly drank | 7 (2.3) | 3 (3.7) | ||
| None | 78 (25.3) | 28 (34.1) | ||
| Alcohol Intake Volume (212) | <22.1 g | 85 (47.8) | 16 (47.1) | 0.172b |
| <44.3 g | 53 (29.8) | 13 (38.2) | ||
| <66.4 g | 23 (12.9) | 4 (11.8) | ||
| ≥66.4 g | 17 (9.6) | 1 (2.9) | ||
| Exercise Partners (216) | Alone | 105 (61.8) | 37 (80.4) | 0.09b |
| Family | 17 (10.0) | 3 (6.5) | ||
| Friend | 10 (5.9) | 2 (4.3) | ||
| People at work | 7 (4.1) | 0 (0.0) | ||
| Circle or club member | 26 (15.3) | 3 (6.5) | ||
| Neighborhood or community | 2 (1.2) | 1 (2.2) | ||
| Others | 3 (1.8) | 0 (0.0) |
a Student’s t-test was used for mean ± SD (normal weight vs. overweight/obese).
b Fisher’s test was used for n (%).
The average age of the normal-weight participants was 54.4 years with a standard deviation of 7.3 years, based on data from 354 individuals. The overweight or obese group had a slightly lower mean age at 53.8 years, with a standard deviation of 7.2 years. This age difference was not statistically significant (p = 0.362).
When considering height, the normal-weight group averaged 162.5 cm (±8.6), while the overweight or obese group stood at an average of 163.1 cm (±8.7); this disparity in height was not statistically significant (p = 0.732).
A significant difference with a p-value surpassing 0.001 was observed in body weight. The normal-weight group averaged 61.2 kg (±10.8), while the overweight or obese group weighed in at an average of 69.7 kg (±11.7).
Examining family structure among the 387 participants for whom data were available: 9.3% (29) of those with normal weight lived alone, in contrast to the 21.4% (18) in the overweight or obese group. This difference was statistically significant (p = 0.003). Focusing on family dynamics, 90.7% (277) of individuals in the normal-weight group were married. Additionally, 47.6% (147) of them had dinner with family members—the highest proportion within this weight category.
Dietary habits showed that 43.2% (134) of the normal-weight participants ate at a regular pace, with 32.6% (101) eating slightly faster. Conversely, in the overweight group, 37.3% (31) ate slightly faster, while 34.9% (29) maintained a normal eating speed.
As for alcohol consumption, 33.4% (103) of the normal-weight group reported a daily intake, while the highest proportion of the overweight group, 34.1% (28), abstained from alcohol.
Binomial logistic regression analysisA binomial logistic regression analysis was conducted on the participants, with the regression coefficients for each survey item presented in Table 2. The OR revealed a significant inverse association between having a high BMI and having a workout companion (OR = 0.39; p = 0.020, 95% CI = 0.18–0.87). A significant association was observed for sex when adjusted odds were considered (OR = 0.40; p = 0.027, 95% CI = 0.18–0.90), while such a connection was not evident for the adjusted odds regarding age (OR = 0.47; p = 0.064, 95% CI = 0.21–0.87).
| Variable (exposure) | Adjusted OR | 95% CI | p-value | |
|---|---|---|---|---|
| Family Structure (small family size) | 2.87 | 1.43 | 5.78 | 0.003 |
| Eating breakfast alone | 1.46 | 0.84 | 2.53 | 0.179 |
| Eating dinner alone | 2.10 | 1.20 | 3.70 | 0.009 |
| Eating speed fast | 1.74 | 1.03 | 2.93 | 0.038 |
| Daily alcohol consumption | 0.37 | 0.18 | 0.73 | 0.004 |
| Occasional alcohol consumption | 0.77 | 0.40 | 1.49 | 0.444 |
| Abstaining from or infrequently drinking alcohol | 2.22 | 1.26 | 3.90 | 0.006 |
| Having a workout companion | 0.47 | 0.21 | 0.87 | 0.064 |
Adjusted OR: adjusted for sex and age. Bold: items for which significantly associated were found.
When accounting for adjusted ORs, obesity was found to be associated with “eating alone” (OR = 2.10; p = 0.009, 95% CI = 1.20–3.70), “small family size” (OR = 2.87; p = 0.003, 95% CI = 1.43–5.78), “fast eating habits” (OR = 1.74; p = 0.038, 95% CI = 1.03–2.93), and “abstaining from or infrequently drinking alcohol” (OR = 2.22; p = 0.006, 95% CI = 1.26–3.90). Conversely, “occasional alcohol consumption” (OR = 0.77; p = 0.444, 95% CI = 0.40–1.49) and “daily alcohol consumption” (OR = 0.37, p = 0.004; 95% CI = 0.18–0.73) were linked with a reduced risk of obesity.
Obesity was found to be associated with certain factors such as “eating dinner alone,” “small family size,” “fast eating habits,” and “abstaining from or infrequently drinking alcohol.”
This study not only considered the usual suspects, such as eating habits and alcohol consumption, but it also introduced newer variables such as “eating dinner alone” and “fast eating habits.” This broadens our understanding of the different elements contributing to obesity. While many might assume that frequent alcohol consumption contributes to obesity, this study found the opposite, suggesting that those who drink infrequently might have higher BMIs. This challenges conventional wisdom and calls for further investigation. With increasing numbers of people living alone or in smaller family units in modern societies, understanding the relationship between these factors and obesity becomes especially relevant. This study provides evidence to address the implications of these societal shifts on public health. This research did not merely focus on a particular age group but rather examined adolescents, older people, and mature adults, providing a more comprehensive view of how obesity trends might manifest differently across age brackets. Despite finding a counterintuitive link between infrequent alcohol consumption and obesity, the study clearly emphasizes that heavy drinking is not a solution and highlights the importance of other healthier lifestyle choices. It acknowledges its limitations and points out the potential benefits of including dietary surveys in future research, setting a direction for upcoming studies in this field.
Previous research has identified a correlation between family structure and children’s BMI23); however, no such relationship has been reported for adults’ BMI. The practice of eating dinner or lunch alone has been associated with obesity in men24), and living alone is considered a risk factor for obesity.
Past research in Japan has established a link between obesity and the practice of eating dinner alone, especially among adolescents and older individuals6,25–27). These findings, mirrored in mature adults, suggest that the habit of dining alone—particularly at dinner—might be associated with obesity24). One hypothesis is that eating dinner alone could foster unhealthy eating habits, thereby contributing to overweight. Additionally, a significant correlation has been noted between obesity and quicker eating rates28,29).
In a review article17), risk factors for obesity were reported as being men, eating quickly, eating dinner before bedtime, being of advanced age, frequently dining out, and heavily consuming alcohol, which underscores the need for lifestyle improvements. Interestingly, in this study, daily alcohol consumption was associated with a lower risk of obesity (OR = 0.37, p = 0.004; 95% CI = 0.18–0.73); this implies a significant relationship between obesity and infrequent alcohol consumption. Past studies have also reported an association between infrequent drinking and a higher BMI30–32). These findings suggest that frequent drinkers may consume less alcohol per occasion, although this study did not include a dietary survey6,27).
It is crucial to highlight that excessive alcohol consumption can lead to negative health outcomes and should not be advocated as a weight management strategy. Notably, among middle-aged Japanese men, healthier Japanese dietary patterns weare negatively correlated with waist circumference33).
Instead, the focus should be on advocating healthier lifestyle choices, such as regular physical activity, a balanced diet, and appropriate portion control. Future research potentially incorporating food frequency and physical activity surveys is highly recommended.
LimitationsThis is a self-administered survey that may be subject to recall bias among respondents. In addition, because the study design was cross-sectional, it was not possible to discuss the causal relationship between BMI and related factors. Furthermore, the results of this study are limited to the mature population of Yugawara and cannot be applied to other areas.
A health survey conducted among mature adults in the city of Yugawara, Kanagawa Prefecture, identified significant associations between obesity and certain behaviors, namely “eating dinner alone,” “small family size,” “fast eating habits,” and “abstaining from or infrequently drinking alcohol.” It is hypothesized that eating alone might lead individuals to consume only their preferred foods, resulting in a nutritionally unbalanced diet. Consequently, it is essential to promote the need for a well-rounded diet.
In conclusion, making changes to one’s lifestyle to enjoy dinners with family and appropriate alcohol consumption is crucial.
Data Availability & Funding: This study was conducted as part of the Yugawara “Kenko” Plan (Yugawara Town Health Promotion Plan and Dietary Education Promotion Plan in Yugawara Town, Kanagawa, Japan) (The first phase of the plan).
Informed consent: Study participants were informed of the study’s aims, and those who completed the survey questionnaire were regarded as consenting to participate.
RK developed the statistical analysis plan. AT performed the statistical analyses. KW contributed to the interpretation of the results. YW implemented the Yugawara Town Health Survey. RH drafted the original manuscript and supervised the conduct of this study. All authors approved the final version of the manuscript for publication.
The authors declare no conflicts of interest.
