Strategies to enhance weight loss should include high vegetable consumption
Current MyPyramid dietary recommendations in the United States include consuming 3.5 to 5.5 cups of Fruits and Vegetables (F&V) each day for 1,600 to 2,600 kilocalorie eating plans. F&V are low in calories relative to other foods and provide nutrients and other phytochemicals not found in other food groups. Consumption of large amounts of vegetables and moderate fruit could reduce overall caloric intake, induce weight loss, or maintain weight long-term in obese and overweight individuals. Therefore, effective strategies to incorporate more vegetables into the daily eating plan are needed.
An intervention to increase F&V intake and reduce caloric intake
A recent study hypothesized that a daily eating plan that included four cups of vegetables and 1 to 1.5 cups of fruit would reduce overall caloric intake and induce weight loss in obese individuals. The study was designed to determine if individuals could maintain a diet high in vegetables and moderate in fruit for 18 months.
Sixty subjects with an average body mass index of 33.5 kg/m2 and an average body weight of 95 kg were recruited and split into two groups. The first group was taught to eat the high vegetable and modest fruit daily plan, while the second group was instructed to lower caloric intake by 500 kcal/day and to reduce total fat to less than 25% of energy. Both groups were instructed to increase physical activity. This was encouraged by providing simple pedometers as incentives.
During the first three months, subjects were provided with two meals each day, five days per week. Periodic Morning educational sessions were held. The vegetable group received 3.5 to 4 cups of vegetables and two fruits, while the reduced calorie group received half the amount of vegetables and the same amount of fruit as the vegetable group. It was hypothesized that after the three-month intervention, subjects would follow the dietary advice and continue to lose weight by consuming high amounts of vegetables and moderate fruit. Weight and body composition were measured at baseline, 3, 12, and 18 months. Serum chemistry profiles were measured at baseline, 3 and 12 months.
Increased F&V intake associated with long-term weight loss
The vegetable group had an increased vegetable intake for at least 12 months. Both groups decreased energy intake over time and it did not differ between groups, which was due in part to reduced fat intake. The reduced calorie intervention group was able to maintain a reduced fat intake for the 18-month period. Both groups lost weight during the first three months, but only the reduced calorie group maintained weight loss at 12 and 18 months. However, the vegetable group did not gain weight in reference to baseline during the observation period. Other benefits recorded in response to this intervention included a total cholesterol reduction at three months, due mostly to a reduction in low-density lipoproteins. This led to improved (lower) cholesterol to high density lipoprotein ratios. In addition, the subjects maintained an increased step count as measured by the pedometers for 12 months.
Recommendations to individuals seeking to lose weight and maintain weight loss should include an emphasis on increasing F&V intake in addition to controlling total energy intake.
Consistently consuming high amounts of vegetables may be more sustainable than counting calories and fat grams from food labels to decrease total energy and fat intake, and high vegetable consumption may assist in maintaining initial weight loss. Weight loss is difficult to maintain over time; therefore, strategies to improve the long-term sustainability of increasing vegetable intake need to be developed. This message needs to be continually repeated to be effective among the general population. When the subjects ate greater than three cups of vegetables each day they lost weight, but they were not able to maintain this level of intake when they were left on their own with only phone and email support.
In addition to modest weight loss or weight maintenance, a diet high in vegetables may reduce the risk of cancer and cardiovascular disease, and improve bone health. Vegetables are nutrient rich and low in energy density and should be part of everybody’s daily eating plan.
- Tanumihardjo, S.A., Valentine, A.R., Zhang, Z, Whigham, L.D., Lai, H.J., Atkinson, R.L. (2009). Strategies to increase vegetable or reduce energy and fat intake induce weight loss in adults. Experimental Biology and Medicine. 234:542-52.
- Valentine, A.R., Whigham, L.D., Tanumihardjo, S.A. (2009). Pedometers are perceived as useful tools for weight loss. Journal of Extension. 42(2):2TOT6.