Vegetarian Protein Sufficient For Appetite Control and Weight Loss

dr alex Interview with:
Dr. Alex Johnstone PhD

Rowett Institute of Nutrition and Health


Medical Research: What is the background for this study?

  • Previous work has indicated that high-protein (30% of diet as protein) meat-based weight loss diets are highly satiating, and reduce the free food intake over a four-week period (1,2).
  • There is limited data on assessing the effect of different types of protein on appetite in weight loss studies (3). Previously, a mixed meat source of protein was used in our high protein diets, but this approach has been criticised both from a policy and public health perspective because of potential negative side effects, especially on gut health (4).
  • There is acceptance that vegetable based weight loss diet may offer protection from diseases (5).
  • It may be that alternative vegetable sources of protein could be satiating, and yet maintain a healthy gut during weight loss, and we set up a study to test this, using soya (plant) protein
  1. Westerterp-Plantenga MS, Nieuwenhuizen A, Tomé D, Soenen S, Westerterp KR. Annu Rev Nutr 2009; 29:21-41.
  2. Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GE. Am J Clin Nutr 2008; 87(1):44-55.
  3. Due A, Toubro S, Skov AR, Astrup A.. Int J Obes Rel Metab Disord 2004; 28(10):1283-90.
  4. Russell WR, Gratz SW, Duncan SH, Holtrop G, Ince J, Scobbie L, Duncan G, Johnstone AM, Lobley GE, Wallace RJ, et al.. Am J Clin Nutr 2011; 93(5):1062-1072.
  5. Clifton P. Brit J Nutr 2012; 108:122–129.

Medical Research: What are the main findings?

  • Over the two weeks, subjects lost similar amounts of weight, on average 2.41 and 2.27 kg on the vegetarian high-protein weight loss and meat based high-protein weight loss diets respectively, with similar reduction in fat-mass and preservation of fat-free mass, due to the high protein component.
  • The vegetarian high-protein weight loss had a similar impact on appetite and motivation to eat as the meat based high-protein weight loss diet.
  • Blood biomarkers improved with weight loss for both high protein diets (plasma cholesterol, low density lipoproteins (LDL), high density lipoproteins (HDL), triglycerides and glucose)
  • There was a greater reduction in total cholesterol with the plant based diet for cholesterol and LDL cholesterol. This finding could be attributed to the composition of vegetarian source of protein (soya), (i.e. fibre, phytochemicals, and other micro and macro nutrients).

Medical Research: What should clinicians and patients take away from your report?

Response: Since appetite control and weight loss was similar in both weight loss diets, vegetarian meals are acceptable to  include in a high-protein moderate carbohydrate weight loss diet. In this context, the diets were 30% protein, 30% fat and 40% carbohydrate from energy. A diet that contains mixed sources of protein is acceptable, to feel fuller for longer during calorie restriction for weight loss.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: Alternative plant sources of protein in the context of weight loss is of interest to achieve a healthy body weight but also sustainable sources for the environment. Also the role of dietary protein with carbohydrate in promoting body weight maintenance after weight loss.

Read more here about our research on sustainable protein :


Research presented at the Association for the Study of Obesity (ASO) in London, UK Interview with: Dr. Alex Johnstone PhD, Rowett Institute of Nutrition and Health, & Aberdeen (2015). Vegetarian Protein Sufficient For Appetite Control and Weight Loss 

Last Updated on March 3, 2015 by Marie Benz MD FAAD