Obesity has reached epidemic proportions in many parts of the world; in 2018, 39% of adults were overweight and 13% were obese [1]. The Global Burden of Disease Study [2] reported that the prevalence of overweight and obesity in Southeast Asia was 22.1% of men and 28.3% of women, with the highest rates in Malaysia at 48.3% and 48.6% for men and women, respectively. The Malaysian National Health and Morbidity Survey (NHMS) 2015 reported a 30.0% prevalence of overweight among adults, while the prevalence of obesity was 17.7% [3]. The report suggests that the prevalence of overweight was significantly higher among males, whereas the prevalence of obesity was significantly higher among females [3]. In addition, the national prevalence of abdominal obesity (waist circumference measurement cut-off values of > 90 cm for males and > 80 cm for females) was 48.6% with a significantly higher prevalence among females [3].

Obesity was quite rare among earlier human populations (hunter-gatherers) because of their active lifestyles that involve physical activity and occasionally unpredictable diet and food shortages [4]. Their dietary requirements were met by consuming uncultivated plants and hunted animals that were extremely lean and low in fats Simple sugars in the form of honey was rare, and there were no dairy foods because of the lack of domesticated animals [4]. Lifestyle changes occurred with the emergence of agriculture during the Neolithic transition, where the cultivation of plants and domestication of animals produced a surplus of food, such as high-carbohydrate crops, including rice, wheat, barley, and tubers. In addition, humans gave up their nomadic lifestyles because of food production and sufficiency [5]. In today's modern world, however, changes in culture and technology had led to changes in the types of food consumed, reduced the need for physical activity, and increased exposure to harmful agents, such as alcohol and tobacco [4].

Poor dietary habits and inadequate physical activity are contributing factors to the development of obesity and many non-communicable diseases (NCDs) [678]. In a review paper, Swinburn et al. [6] classified the evidence of the role of diet, nutrition, and physical activity for the prevention and obesity into several categories: ‘convincing’, ‘probable’, ‘possible’, and ‘insufficient’. The intakes of dietary fiber (non-starch polysaccharides) and physical activity were categorized under the ‘convincing’ category and were highly protective against obesity, whereas high intakes of foods that are energy dense but low in micronutrients along with sedentary lifestyles were ‘convincing’ risk factors for obesity. In addition, the frequent intake of sugar-sweetened beverages and heavy marketing strategies used by fast food outlets and manufacturers of energy-dense foods were identified as ‘probably’ obesity risk factors [6]. The national policies on diet-related NCDs in low- and middle-income countries are inadequate and policy responses addressing the challenges of NCDs need to be scaled up to improve the dietary quality and physical activity [7]. The global epidemic of obesity is related to an unbalanced energy intake as the main driver of weight gain as well as dietary quality, which affects the energy balance through complex mechanisms [8]. In addition, the food environment, urbanization, reduced physical activity, and other factors in a broader environmental, societal, and policy context play important roles in explaining the rapid increase in obesity rates [89].

In this study, the dietary intakes were measured in a sample of Malaysian adults and gaps between the recommended levels and current intakes were examined. This study also comparesthe dietary intakes between male and female participants to determine the association between the dietary intake variables and the obesity indicators, i.e., body mass index (BMI) and waist circumference (WC) measurements.

Obesity is a consequence of a prolonged positive energy balance and can be influenced by other factors, such as the host (individual), environment (surroundings to which individuals are exposed to), and vector (food and drink consumed) interacting in complex ways that affect the dietary intake and activity patterns [8]. The aims of this study were to (1) assess the dietary intakes in a sample of free-living adults in Malaysia and (2) determine the association between dietary intake variables with the BMI and WC measurements. First, an assessment of the anthropometric indices showed that the proportion of overweight (30.8%) and obese (22.0%) participants in the present study were similar to the proportion of overweight (32.4%) and obese (18.5%) in Malaysian adults in the National Health and Morbidity Survey 2014: Malaysian Adults Nutrition Survey (NHMS 2014: MANS) [17]. In this national level survey, the prevalence of abdominal obesity was 20.0% with a significantly higher prevalence among females (31.8%) and males (9.6%). The proportion of participants with abdominal obesity in the present study was 47.5% with a higher proportion among female participants (53.3%) than their male counterparts (37.0%). This is a worrying trend because the increased prevalence of obesity and abdominal obesity among Malaysians has been and will continue to be a significant burden on the medical costs to treat obesity-related conditions [17]. Sex differences in the anthropometric indicators could be distinguished in the present study, where female participants had a significantly higher BMI but lower WC measurements. Significantly higher BMI and WC measurements were also detected among participants who were married/living with a partner but lower BMI and WC measurements were observed among participants with higher education levels. In the 2014 MANS study, obesity was most prevalent among Malaysians who were married and among those with tertiary level education [17]. In addition, another health survey among adults in five different regions in Malaysia indicated a 33.6% and 19.5% prevalence of overweight and obesity, respectively, with a higher prevalence among females compared to males [18].

In this study, the median energy intake and percentage of total energy contributed by the macronutrients were comparable to the NHMS 2014: MANS, suggesting that the participants had similar dietary intakes to that of an average Malaysian adult. The median energy intake of Malaysians recorded in the NHMS 2014: MANS report [13] was 1466 kcal/day with significantly higher values among men [17]. The median intake of macronutrients among the NHMS 2014: MANS study participants were 195 g of carbohydrate, 57 g of protein, and 46 g of fat. In contrast, the median percentage of the total energy contributed by macronutrients was 55% for carbohydrates, 16% for protein, and 29% for fat. Similar to the present study, the protein intake of adults in the NHMS 2014: MANS slightly exceeded the recommended percentage of 10–15% [15], whereas the carbohydrate and fat intakes were within the recommended percentage.

The mean protein intake of the participants in the present study exceeded the amount recommended by the RNI for Malaysian adults, as well as the percentage of energy contribution for protein that ranged from 10–15% [15]. The mean percentage of energy contributed by fat intake at 29.2% almost exceeded the recommended range of 20–30% [15]. The carbohydrate intake of the participants appeared to have been displaced by the higher protein and fat intake in the diets. As a side note, the average serving of meat consumed among the participants was relatively high with 2.0 ± 1.0 servings per day, which was significantly higher among males. The trend of lower carbohydrate and higher protein intake was also observed in a sample of government servants in an urban area in Malaysia [19], as well as in a larger national survey [17].

A trend of higher protein intake or nutrition transition of increased protein intake from meat and poultry with a decreased carbohydrate intake has been observed globally and was reported in the national food balance sheet [20]. The Food and Agriculture Organization of the United Nations (FAO) [20] reported that the dietary patterns are shifting towards increasing demands and consumption of food from animal origins, including fish. For example, the World Resources Institute reported that the global demand for beef and animal-based foods will likely increase by 95% and 80% between 2006 and 2050 [21]. The growth is expected to be concentrated in urban areas of emerging economies, such as China and India [16]. Malaysia is an upper-middle income country [22] with a thriving economy and its society is currently experiencing a nutrition transition [23]. Indonesia is also undergoing a nutrition transition, where the total energy intake was comprised higher proportions of protein and fat consumption in recent years [23]. The increase in protein intake is consistent with the increased consumption of meat and dairy products, which was parallel to the improving economy and living standards [23]. Nevertheless, more evidence-based prospective observational studies will be needed to confirm this trend. A systematic review and meta-analysis of observational studies confirmed that red and processed meat consumption is associated directly with a higher BMI and WC [24]. In addition, a high intake of meat also predicted more weight gain [25].

An assessment of the dietary intake showed that the consumption of fruits (< 1 serving) and vegetables (< 2 servings) by the study participants was substantially lower than the levels suggested by the MDG, which recommended two daily servings of fruits and three daily servings of vegetables [16]. This has also contributed to the low dietary fiber intake among the participants. Low fruit and vegetable consumption patterns were also observed among the local Malaysian communities in other studies [192627] as well as in the neighboring country of Indonesia, which shares similar socio-cultural practices with Malaysia [28]. The health benefits of a sufficient daily intake of fruits and vegetables in the prevention of major diseases, as well as morbidity and mortality, have been well documented [1629] and the higher consumption of non-starchy vegetables and fruits have been associated with a lower risk of weight gain and obesity [25]. The high intake of dietary fiber was associated with less weight gain, while the intakes of both fruits and dietary fiber were protective against large increases in WC measurements [25]. Therefore, the consumption of fruits and vegetables, as well as foods high in fiber, such as whole grains, should be strongly encouraged and advocated.

In terms of other food groups, the participants had low intakes of milk and milk products that contributed to the low calcium intakes. The number of servings of fats, oils, and sweets combined was approximately nine servings per day, whereas the recommendations clearly indicated that the items from this food group should be consumed in limited amounts. With the mean total sugar intake at 28.4 ± 23.3 g per day and approximately 30.0% of the total energy intake was from fat, it is fair to say that the calorie intakes of the participants of this study were mainly from a high proportion of energy from sugars and fats. Studies have suggested that high intakes of sweets and desserts are linked to more weight gain [2530]. With regards to the correlations between the dietary intakes with obesity indicators, there were no correlations between the total energy intake and macronutrient intakes with the BMI and WC measurements in this study (Table 5). On the other hand, a local study conducted on overweight and obese Malay women reported that the respondents' body weight status is affected by the energy intake, not the macronutrient composition because significant correlations were detected between the total energy intake with the BMI and WC measurements [31].

Further statistical analysis of the data showed that among the dietary intake variables, only the carbohydrate intake was inversely associated with the BMI (Estimate b = −0.008) and WC measurement (Estimate b = −0.019). Other studies also demonstrated associations between the carbohydrate intake and obesity. For example, the cross-sectional Canadian Community Health Survey Cycle 2.2 reported that the risk of overweight and obesity problems was reduced in all quartiles of the carbohydrate intake (between 290 to 310 g/day carbohydrates) compared to its lowest intake category [32]. The authors concluded that a low carbohydrate intake (below 47% of total energy) in healthy adults was associated with a higher likelihood of being overweight or obese. Furthermore, the risk of overweight and obese was reduced to the lowest rate by consuming 47% to 64% of the energy intake from carbohydrates, after accounting for age, sex, income, education, physical activity, and total energy intake [32].

Merchant et al. [32] and Roberts et al. [33] explained the inverse association between carbohydrate intake and body weight. Individuals who consumed more carbohydrates tend to consume larger amounts of fiber, fruits, and vegetables, and less saturated fat [3233]. Dietary carbohydrates from fruits, vegetables and whole grains also have a low glycemic load and are beneficial to human health [3233]. In addition, diets lower in total and saturated fat and higher in carbohydrate intake from whole grains or high-fiber foods, vegetables, and fruits were reported to be protective against weight gain in postmenopausal women in the Women's Health Initiative Dietary Modification Trial [34]. On the other hand, there are also contradicting opinions regarding the relationship between dietary carbohydrates and body weight. The results from an observational study in the USA suggest that the glycemic index of different types of carbohydrates was positively associated with BMI, but not the glycemic load, daily carbohydrate intake, or percentage of energy from carbohydrates [35].

Halkjær et al. [36] examined the associations between the total energy intake and energy intake from macronutrients with the 5-year changes in WC measurements in a large cohort in Denmark after adjusting for age, sports activities, and smoking habits. The authors stated that the total energy intake and energy from macronutrients were not associated with the WC among the respondents after five years, with the exception of an inverse association with animal protein [36]. The intake of refined carbohydrates, such as refined grains, potatoes, and foods with simple sugars was positively associated with the increase in WC, whereas negative associations were detected with carbohydrates from fruits and vegetables [36]. Similar to Merchant [32], only the carbohydrate quantity was investigated in this present study, not the quality or source of carbohydrates, which is a limitation of this study. Future studies should examine the association of carbohydrate or macronutrient intake with obesity to identify the sources or quality of macronutrients clearly. The association detected between the carbohydrate intake with BMI and WC measurements was also rather weak. Nevertheless, because this study was cross-sectional in nature, where the measures of BMI, WC, and dietary intakes were taken at the same point in time, it is difficult to read the association of the dietary intake to BMI and WC. For example, the participants' perception of being overweight and obese may lead the individuals to changing their dietary habits or practice dieting to reduce their body weight. Therefore, prospective observational studies or intervention studies will be needed to relate the dietary intake with body weight.

One of the strengths of this study was the use of standardized measures to obtain the dietary intake, BMI, and WC measurements. Dietary intake data were obtained through a series of 3-day 24-hour dietary recall interviews inclusive of weekdays and weekends by trained interviewers, and an analysis of nutrient intakes using the Nutritionist Pro software was performed by the researchers themselves. Because this study was cross-sectional, the cause and effect could not be inferred. The generalizability of the sample against the Malaysian population may be limited due to the small sample size and the recruitment approach. Nevertheless, this dataset of dietary intakes provides rich and reliable information on the dietary intakes of Malaysian adults. Follow-up studies will be needed to identify the dietary factors that affect obesity in Malaysian adults.

In conclusion, this study assessed the dietary intakes among a sample of free-living Malaysians and identified their dietary intake patterns in comparison to existing guidelines and recommendations. The associations of dietary intake with obesity indicators were also investigated. This study revealed high proportions of overweight and obesity among the study participants. Although the energy intake did not exceed the recommended values, the protein intake was higher than the recommended amounts. The intake of fruits and vegetables as sources of dietary fiber were below the recommendations and the intake of sugars and fats were substantially high among the participants. This study suggests higher intakes of complex carbohydrate-rich foods choices, such as whole grains, fruits, vegetables, and legumes. Overweight and obesity increase the risk of many health issues and is a significant burden on the country's economy and healthcare costs. Changes to Malaysians' dietary intake and lifestyle are urgently needed to halt the escalating prevalence of overweight and obesity.