I don't use VSN. But sure, when you get a chance.
In the meantime here is a decent list of literature regarding needing a deficit to lose. Different food types do not matter in terms of weight loss. Energy balance does.
Studies consistently show that weight loss is primarily determined by caloric intake, not diet composition (Hill et al.,1993)
In all cases, individuals on high-fat, low-CHO diets lose weight because they consume fewer calories (Freedman et al. 2001)
Alford et al. (1990) manipulated CHO content of low calorie diets (1200 kcal/d) to determine possible effects on body weight and body fat reduction over 10 weeks. Women in each diet group consumed either a low-, medium-, or high-CHO diet. The low-CHO diet was 15% to 25% CHO (75 g/d) (30% protein, 45% fat), the moderate-CHO diet was 45% CHO (10% protein, 35% fat), and the high-CHO diet was 75% CHO (15%protein, 10% fat). Weight loss occurred in all groups, but there was no significant difference in weight loss among the groups. Percent body fat loss, based on underwater weighing was similar among the groups. Alford et al. concluded, “there is no statistically significant effect derived in an overweight adult female population from manipulation of percentage of CHO in a 1200-kcal diet. Weight loss is the result of reduction in caloric intake in proportion to caloric requirements.” (Freedman et al., 2001)
Golay and colleagues (1996) followed 43 obese patients for 6 weeks, who received a low cal diet (1000 kcal), and participated in a structured, multidisciplinary program that included physical activity (2 h/d), nutritional education, and behavioral modification. The diet contained either 15% CHO (37.5 g), or 45% CHO. Protein content of the diets was similar (approx: 30%) and fat made up the difference. After 6 weeks, there was no significant difference in weight loss between the different diet groups. Significant and similar decreases in total body fat and waist-to-hip ratios were seen in both groups.*
Wing and colleagues (1995) confined 21 severely obese women to a*metabolic*ward for 31 days. They were randomly assigned to a non-ketogenic or ketogenic (10 g CHO) liquid formula diet (600 kcals) for 28 days. At end of study weight losses were similar.*
A portion of weight loss in the early stages of low carb dieting is due to water losses (Bell et al., 1969; Van Itallie et. al. 1975), however, the majority of weight loss in the early stages of a mixed diet is primarily due to loss in body fat (Yang and Van Itallie, 1976); other studies support this finding. Losses of protein and fat are about the same when following a ketogenic, or isocaloric, non-ketogenic diet (Golay et al. 1996)*
"In the short-term, low-CHO ketogenic diets cause a greater loss of body water than body fat." (Freedman et al. 2001)
"Low-CHO diets are high in fat, especially saturated fat, and cholesterol. They are also high in protein (mainly animal), and provide lower than recommended intakes of vitamin E, vitamin A, thiamin, vitamin B 6, folate, calcium, magnesium, iron, potassium and dietary fiber." (Freedman et al. 2001). In these instances supplementation is required for proper nutrition.*