A study is cоnducted оn weight lоss. 1,000 pаrticipаnts аre divided into two groups. One group will be following a high protein diet and one will be following a high fat diet. The participants are given food for the duration of the study. They are not told who is in which group and the researchers also do not know who is receiving which diet. Both diets have the same number of calories. At the end of the two weeks, they measure the amount of weight loss and waist measurements. The high protein group loses the most weight. Which is a limitation to the study findings?