Did they design the two meal plans within similar calorie intake? If the whole vegan group is losing weight, it means the vegan diet plan has much less calorie

Did they design the two meal plans within similar calorie intake? If the whole vegan group is losing weight, it means the vegan diet plan has much less calories to the point of calorie deficiency to cause weight loss. It looks like the trial was designed to skew the results. The trial becomes comparing a short term dieting plan to a full meal plan. It’s known that short term fasting and calorie restricted meals do improve health overall.