By Stephanie Cailor, PharmD Student
You have probably heard the common dietary recommendation that you should eat more fruits and vegetables as a part of a healthy diet. WebMD provides some simple diet tips including one that correlates specifically with this theme. They explain that by “eating more fruits and vegetables, you shouldn’t feel as hungry because these nutrient-rich foods are also high in fiber and water, which can give you a feeling of fullness,” a claim that is supported by much research.1, 2 So how exactly does fiber play a role? Fiber is a component of food that is difficult for the body to digest. Two types of fiber exist: soluble fiber, such as that found in citrus fruits, strawberries, celery, and green beans, and insoluble fiber, found in foods such as broccoli, cabbage, and grapes. Soluble fiber retains water and slows digestion in the stomach and intestines; whereas, insoluble fiber works by adding bulk to the stool in order to speed up the passage of food through the stomach and intestines.3 For this reason, among others, the World Health Organization recommends that adults eat a minimum of 400 grams of fruit and vegetables per day to prevent health conditions such as obesity.4 To bring this number into perspective, roughly half of each plate should be filled with fruits and vegetables. Further examples and information regarding serving sizes can be viewed at www.choosemyplate.gov/food-groups/.5 While the task of eating more fruits and vegetables may seem simple, is this general recommendation to help lose weight failing to tell us the whole story?
The claim that adding fruits and vegetables to the diet can help with weight management may be correct, but only increasing fruit and vegetable consumption may not lead to weight loss. A recently published meta-analysis reviewed the results of 7 research studies on this subject.6 Each of these studies looked at the impact of increased dietary intake of fruits and vegetables on weight loss; however, none saw a significant effect. One study involving 90 adults utilized an 8 week intervention that added either 0 grams, 300 grams, or 600 grams of fruits and vegetables to daily diet. The study concluded that groups increasing their fruit and vegetable intake lost some additional weight, but the amount was not statistically significant.7 Another study looked at adult women who increased the intake of their fruits and vegetables to 9 servings a day. The body weight of these patients changed very little, with no statistically significant reduction in weight loss over the course of the study.8 There are a few reasons why the included research studies may show the shared conclusion of no significant weight loss due to eating more fruits and vegetables. Some of the studies may not have looked long enough to see the effects of eating more fruits and vegetables on body weight. Others may have not had a large enough increase in fruits and vegetables in the diet to show any weight loss effects. Accordingly, more research needs to be done on this topic before a definitive statement can be made.
Overall, this meta-analysis concludes by stating that while eating more fruits and vegetables does promote a healthy lifestyle, in order to lose weight, other efforts are necessary to achieve desired outcomes.6 For example, adding fruits and vegetables without cutting out other unhealthy foods, primarily those with high calorie counts, will not provide desired weight loss effects.9 Other supporting research emphasizes that significant weight loss results can be seen by reducing caloric intake and balancing the diet with fruits and vegetables.4, 10
As a future pharmacist, I believe that eating more fruits and vegetables as a part of a healthy diet is beneficial due to their overall low caloric content and the fiber they contain. To lose weight, though, it is important to reduce the amount of unhealthy foods in the diet. Being healthy is a lifelong pursuit that does not consist of simply changing one bad habit. Alongside a healthier diet, it is also important to be physically active. For physical activity to provide health benefits, adults should spend 150 minutes per week doing moderate intensity aerobic activity (such as walking) and at minimum 2 days per week completing muscle strengthening activities, which includes strength training or endurance exercises.11 Small steps towards a healthy lifestyle for some people could mean adding one new vegetable to their plate tomorrow or not buying chips at their next trip to the grocery store. Others may choose to take a walk around their neighborhood every day for the next week. What are some unhealthy lifestyle and diet habits that you could change today to help you get on track for weight loss?
- Smith, M. W. (2014). 15 Best diet tips ever. Available from: http://www.webmd.com/diet/ss/slideshow-best-diet-tips-ever. Accessed on October 17, 2014.
- Tohill, B. C. (2005). Dietary intake of fruits and vegetables and management of body weight. World Health Organization.
- Dugdale, D. (2012, September 2). Soluble and insoluble fiber: MedlinePlus Medical Encyclopedia Image. Retrieved November 1, 2014.
- Amine, E., Baba, N., Belhadj, M., Deurenbery-Yap, M., Djazayery, A., Forrester, T & Yoshiike, N. (2002). Diet, nutrition and the prevention of chronic diseases: report of a Joint WHO/FAO Expert Consultation. World Health Organization.
- Dietary guidelines for Americans, 2010. (2010). Washington, D.C.: U.S. Dept. of Health and Human Services, U.S. Dept. of Agriculture.
- Kaiser, K. A., Brown, A. W., Brown, M. M. B., Shikany, J. M., Mattes, R. D., & Allison, D. B. (2014). Increased fruit and vegetable intake has no discernible effect on weight loss: a systematic review and meta-analysis. The American journal of clinical nutrition, 100(2), 567-576.
- Whybrow S, Harrison CL, Mayer C, James SR. Effects of added fruits and vegetables on dietary intakes and body weight in Scottish adults. Br J Nutr 2006;95:496–
- Maskarinec G, Chan CL, Meng L, Franke AA, Cooney RV. Exploring the feasibility and effects of a high-fruit and -vegetable diet in healthy women. Cancer Epidemiol Biomarkers Prev 1999;8:919–
- Sacks, F. M., Bray, G. A., Carey, V. J., Smith, S. R., Ryan, D. H., Anton, S. D., … & Williamson, D. A. (2009). Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. New England Journal of Medicine, 360(9), 859-873.
- Wing, R. R., Hill, J. O. (2001). Successful weight loss maintenance. Annal Review of Nutrition, 21(1):323-341.
- Physical Activity Guidelines Advisory Committee. (2008). Physical activity guidelines advisory committee report, 2008. Washington, DC: US Department of Health and Human Services, 2008, A1-H14.