A cross-sectional analytical study was conducted between March-July 2018. The study population was working age persons in Phnom Penh capital city of Cambodia. This research project and tool got approval from the Khon Kean University Ethics Committee in Human research (HE582071). The sample size was calculated by using the formula required for determination of sample size for estimating single proportion by taking a previous study done on fast food consumption and overweight and obesity in South Africa, which showed 49.7% proportion of fast food consumption in the previous seven days, 95% confidence interval and a margin error of 5% [17,26]. Therefore, the total number of samples was 749. The samples were selected by applying a multi-stage random sampling technique. A simple random sampling was used to select 12 communes from 5 districts in Phnom Penh capital city of Cambodia. Then, 749 households were selected from the total 44,436 households by applying systematic random sampling technique among those 12 communes in proportional to size of the population. Finally, one member of each household aged 18-59 years was selected or randomly selected if the household had more than one member of the mentioned age group. The inclusion criteria of the respondents were the residents living in Phnom Penh capital city for at least one year, willing to participate in the study, having no communication problems with the researcher. The exclusion criteria were those who were unable to move, or suffering from the debilitating disease. The participants were requested to respond to a structure questionnaire interview in their own house and anthropometric measurements were also performed.

A structure questionnaire was developed based on the research questions and relevant literatures. The questionnaire consisted of four parts:

Part 1: Demographic and Socioeconomic Characteristics: gender, age, marital status, educational attainment, occupation sectors, family members, personal monthly incomes, personal monthly expense, family monthly incomes and family monthly expenditures. Part 2: Health Status and History: family history of overweight and obesity, chronic disease (diabetes, hypertension) any treatment or advice, understanding on nutrition fact label of food. Part 3: Lifestyle and Behaviours: tobacco uses, alcohol consumption, food habits, physical activities and sedentary behaviour. Part 4: Situations of fast food consumption, questions were assessed in this part including: Have you ever consumed fast food in the past one month? What types of fast food do you consume? How often do you consume fast food? On what occasions do you consume fast food? What do you consume fast food for? Whom do you consume fast food with? How much do you spend on fast food consumption? Where do you consume fast food from? How do you get the information about fast food?

Measurement of Outcome: Body height in centimeters (cm) and weight in kilograms (kg) were measured to the nearest 0.1 cm and 0.1 kg by using metering object and digital weighing instrument. Overweight and obesity defined as BMI≥23 Kg/m2 by WHO [27] for Asian cut-off points was the main outcome of the study. The questionnaire has been verified for content validation by 5 experts and revised to improve its validity. Moreover, the questionnaire was tested for reliability by calculating Cronbach’s alpha among 30 participants in other districts of Phnom Penh capital city. The Cronbach’s alpha coefficient was 0.857.

The respondents were asked to sign the written consent form if they were willing to participate in the study after Ethical clearance and approval was obtained from the office of the KhonKaen University ethics committee in human research. All confidentiality of data was fully assured. A structured questionnaire interview was conducted to collect the data from 3 interviewers who were trained and standardisation for data collection skills.

Descriptive analysis were conducted using a frequency distribution for the categorical variables and mean with Standard Deviation (SD) for continuous variables. Both bivariate and multiple logistic regression were applied to identify the association between fast food, overweight and obesity by adjusting other covariates. All statistically significant variables in bivariate logistic regression having p-value less than 0.25 were added to the multiple logistic regressions. Crude Odds Ratio (ORs) and Adjusted Odds Ratios (AORs) were calculated and reported with 95% confident intervals. All statistical tests were two-sides and p-value less than 0.05 were considered statistically significant. Stata version 13 (College Station, Texas, USA) was used for analysis.

The baseline characteristics of the 749 respondents in the study showed that half of them were female (50.20%) with the mean age 32.26±11.12 years ranging from 18 to 59-year-old. Most of respondents were married (53.94%), high school (31.91%) and private company staff (28.97%). The median family size was 4 persons. As many as 47.93% of respondents lived with their spouses. The median monthly income and expense were 300 USD and 200 USD respectively; however, the lowest earning was only 40 USD. Less than a quarter (24.57%) of respondents had family history of overweight, obesity and diabetics (18.96%). About a quarter (25.77%) had hypertension. Only (10.41%) smoked; however, more than half (54.34%) drank in the last 12 months [Table/Fig-1].

Almost one third of the working age persons consumed fast food during the past one month (62.75%: 95% CI: 59.28%-66.22%). The most common fast food consumed were sweetened soft drinks such as coffee with milk, fruit Juice, energy drinks, cocoa brewed (36.65%), followed by carbonated soft drinks (17.76%), Meat (roast/toast/grill/fried chicken, bacon, pork, steak, meat ball, sausage and ham) 16.15%, Pasta (pizza, spaghetti, macaroni) 14.15%, meat with bread (hamburger, sandwiches, hot dog) 10.15% and Bakery (cake, doughnuts, cookies, biscuits, cracker) 4.54% [Table/Fig-2].

Nearly half (42.55%) of the respondents consuming fast food drank sweetened soft drink 7 times per week. Carbonated soft drink was consumed almost equally from 1 to 7 times per week. However, Pasta, Meat with bread and Bakery were the types of fast food which were consumed the least [Table/Fig-3].

The overall prevalence of overweight and obesity were 38.72% (95% CI: 35.22-42.21). The bivariate analysis indicated that fast food consumption, sex, age, marital status, occupation, family size, whom you live with, income, family history of overweight and obesity, hypertension, diabetes, smoke, drinking alcohol, fruit consumption, exercises, screen time, sleeping time and soft drink consumption were significantly associated with overweight and obesity [Table/Fig-4].

The final model after adjusting for other covariates in the multiple logistic regression analysis showed that fast food consumption was significantly associated with overweight and obesity (OR adj=2.00; 95% CI: 1.39-2.88; p<0.001). Other significant covariates were; male gender (OR adj=1.53; 95%CI: 1.06-2.20; p=0.020, adults age 31-59 years (OR adj=3.02; 95% CI: 1.98-4.62; p<0.001, married (OR adj=1.69; 95% CI: 1.12-2.54; p=0.012, had family history of overweight and obesity (OR adj=1.50; 95% CI: 1.01-2.22; p=0.043, drank alcohol (OR adj= 1.60; 95% CI: 1.10-2.31; p=0.013) and had hypertension (OR adj=2.14; 95% CI: 1.45-3.19; p<0.001) [Table/Fig-5].

In the current study, the overall combined prevalence of overweight and obesity (BMI ≥23 kg/m²) was 38.72% with the classification of overweight (BMI ≥23.0-24.99 kg/m²) was 16.69% and obesity (BMI ≥25 kg/m²) was 22.03%, respectively. The prevalence of current study is higher if compared to the previous study conducted by Ministry of Health of Cambodia because it was conducted in the whole country and used different cut-off point [24]. Comparing the study with the result of the national Thai food consumption showed that the prevalent of overweight and obesity in Thai population was similar to the current study (40.9%) [28]. In addition, a study in Malaysia [29] found that the prevalence of overweight and obesity were 33.6% (95% CI= 32.2, 35.0) and 19.5% (95% CI= 18.3, 20.7) respectively. The prevalence of overweight and obesity among adults in Northeast India by using the same WPRO for ASEAN standard cut-off point was similar in total, but lower for obesity, as for overweight it was 32,57% and obesity was 10.77% [30]. In urban Srilankan adults overweight was 32.7% and obesity was 18.5% [31]. Over-nutrition prevalence was very high in Accra Metropolis, Ghana of which there were17.8% obese and 37.8% overweight [32]. Previous studies indicated that fast food consumption was strongly associated with overweight and obesity [33-36].

The multivariable analysis of this study confirmed that fast food consumption was significantly associated with overweight and obesity among working age persons in Phnom Penh city, Cambodia. Those who consumed fast food were 2.00 times more likely to be overweight and obese. The possible explanation is that fast food contains high calories, sugar, salt, high fat contents, but low of micronutrients and fiber that could provoke the changes of appetite controlling in human organism [18,37].

Some studies indicated the higher prevalence of overweight and obesity in male compare to female [13,38,39], in this study, male gender was 1.54 times higher odds of being overweight and obesity when compared to female. In contrast to this finding, other studies found that there was higher prevalence among female than male [29,40-42]. The reasons that male has higher prevalence of overweight and obesity compared to female may be related to body image and beauty concern of women. Most of women in present study engaged in some types of weight control including physical activities and consumed less. Furthermore, due to societal traditions, women play an important role in family, community life and economy, even though women were busy in their job or work, women still had shared time with their household chores that burn out the calories.

Participants whose age was 31-59 years were 2.89 times more likely to be overweight and obese when compared to those whose age was 18-30 years. As a result, it can be seen that overweight and obesity increases significantly with age. It might be due to the fact that with the increase in age, the engagement in physical activities decreases which contributed to overweight and obesity [31,42,43].

Those who were married were 1.74 times more likely to be overweight and obese than those who were unmarried. Reasons might be explained, that people who were married become more comfortable with their lifestyle and appearance and let themselves go whereas single person may spend more effort to keep fit in order to be attractive [30,32,45].

Participants who had family history of overweight and obesity were 1.51 times more likely to be overweight and obesity. In term of environmental factors in family, family lifestyle and poor dietary pattern especially wrong perception of parents viewing overweight and obesity was not potential risk factors of subsequent health complications that might affect behaviours of their offspring which related to overweight and obesity. Concerning biological nature, the genetic might influence offspring to develop this condition [40,43].

Those who had hypertension were 2.19 times more likely to be overweight and obese compared to those who had no hypertension. The reason may be, our study involve comparatively older age respondents, therefore, it might have more chances to get greater adiposity [29,45,46].

Finally in the present study, it was found that those who drank alcohol were 2.19 times more likely to be overweight and obese compared to those who did not drink alcohol. This could be due to more calories without right mix of nutrients are consumed. Furthermore, drinking alcohol might change the lifestyle, not engaged in physical activities [32].

This study had some limitations. First, currunt study is focused and carried out in the capital city, therefore it could not represent the whole population of Cambodia. Second, as the current study was a cross-sectional analytical study, it could not infer causality; therefore, further study with operational research or longitudinal cohort study design is recommended to provide the better understanding of the causal relationship between fast food consumption and overweight and obesity among working age persons in Cambodia.

This study revealed that the majority of fast food consumer was overweight and obese among working age population in Cambodia. Since Cambodia economy has been increasing in the last decade therefore the lifestyles of the people have been changed. It shows that Cambodian has a significant problem of fast food consumption and overweight. Therefore, findings of this study will develop evidence-based approaches to address these problems which will help in advancing prevention and management of fast food consumption and will reduce over-nutrition.