The Dietary Guidelines Advisory Committee found vegan, vegetarian and Mediterranean to be the most environmentally friendly diets.
Researchers from the nonprofit organization Physicians Committee for Responsible Medicine write in the American Journal of Health Promotion that an 18-week plant-based diet can boost employee productivity and reduce anxiety, depression and fatigue.
The employee cafeteria menu featured vegetable hummus sandwiches, seasonal leafy green salads, black bean chili and various fruits and vegetables rich in vitamins and minerals during the study period.
"Lunch and learn" sessions were also held on a weekly basis that encouraged employees to acquire new cooking skills and learn more about healthy food.
The authors report that study participants lost an average of 10 lb and experienced a 13-point drop in low-density lipoprotein (LDL) cholesterol, as well as improved blood sugar control.
Improvements in anxiety, depression, fatigue and general health were also reported, measured using the Short Form Health Survey (SF-36) and the Work Productivity and Activity Impairment Questionnaire (WPAI).
The researchers note that some of the carbohydrate-rich foods in the study, including brown rice, oats and rye bread, help to regulate levels of the mood-controlling chemical serotonin in the brain as well as being good for other organs.
"The same foods that curb the risk for obesity, heart disease and diabetes may help boost overall mood," study author Dr. Neal Barnard explains. "In the evolving landscape of neurological research, a plant-based diet may help in treating symptoms of anxiety and depression."
Dr. Barnard also hypothesizes that improvements in physical health lead to employees becoming more physically and socially active, which in turn leads to improved mood and quality of life:
"Helping employees improve their health through a plant-based dietary intervention is a win-win situation for employees and the company. Who doesn't want to feel great, increase energy and maximize productivity in the process?"
The authors remind that obesity currently affects 35% of American adults. Obese people are associated with an increased health care cost of $1,429 annually, the researchers say, compared with people of a normal weight. Costs for lost productivity associated with obesity are estimated to total $73 billion each year.
2015 dietary recommendations advocate environmentally friendly plant-based diet
The Dietary Guidelines Advisory Committee (DGAC) have also released a 571-page report detailing their recommendations to the Department of Health and Human Services (HHS) and the US Department of Agriculture (USDA), in which the federal committee calls for the adoption of plant-based diets, in addition to taxes on desserts and electronic monitoring of how long Americans spend in front of the TV.
This plan to "transform the food system" is open to public comment for 45 days and will be used as the basis for the government's 2015 Dietary Guidelines for Americans - guidelines developed for making decisions about national health objectives, nutrition education and government food assistance programs.
As well as helping to curb the growing obesity epidemic, the DGAC believe that a plant-based diet will address climate change concerns:
"The major findings regarding sustainable diets were that a diet higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts and seeds, and lower in calories and animal-based foods is more health promoting and is associated with less environmental impact than is the current US diet."
The committee found vegan, vegetarian and Mediterranean diets to have the least greenhouse gas emissions and be the most environmentally friendly.
"Current evidence shows that the average US diet has a larger environmental impact in terms of increased greenhouse gas emissions, land use, water use and energy use, compared to the above dietary patterns," the report reads. "This is because the current US population intake of animal-based foods is higher and plant-based foods are lower than proposed in these three dietary patterns."