Nutrition is an integral part of economic development, since it influences workers’ health and productivity. This study evaluated the usual nutrient intakes and food sources of working adults. We conducted a cross-sectional survey that involved 1264 selected working adults aged 19 to 59 years old from randomly selected job sectors. Quantitative dietary data was collected by a 2-day, non-consecutive 24 h recall, while a dietary diversity questionnaire was used to assess the types and frequency of foods consumed. Physical activity was measured using the World Health Organization global physical assessment questionnaire. The prevalence of inadequate intakes, defined as the percentage of adults with intakes less than the estimated average requirements (EAR) or acceptable macronutrient distribution ranges (AMDR) were estimated using the PC—Software for Intake Distribution Estimation (PC-SIDE) program. The mean daily energy intake of working adults was 1768 kcal/day or 74% of the Estimated Energy Requirements (EER) for this age group. The percentage contribution to the total energy of fats (58%) and proteins (34%) were excessively high. Consumption of fruits and vegetables was only 30% and 40% of the recommended nutrient intake, respectively. Salt intake was 52% above the adequate intake. Nutrient inadequacy was high in almost all nutrients, including iron (99%), folate (97.9%), riboflavin (95.8%), calcium (94.7%), vitamin C (87.3%), and thiamin (76.6%). The top five food sources of energy included rice (35.6%), pork (15.1%), fats and oils (4.7%), chicken (4.4%), and bread (3.8%). Energy and nutrient intakes of working adults is extremely sub-optimal due to the consumption of few nutrient-dense foods. This may pose a triple burden of malnutrition if left unsolved.