Hi Diane,
DianeJ wrote: So the question is- do you think one would lose weight by substituting a fairly healthy vegan diet( prob. containing some soy, and meat subs, etc, but lots of plants, whole grains, fruits etc) but NOT the McD. plan- for a "fairly healthy" meat-eating, low-fat dairy, some sugar diet.
When you look at studies, vegans tend to have a slightly lower BMI then the general population but this does not guarantee that a vegan diet will result in weight loss or the maintenance of ones weight loss. When you look at some studies on vegan diets that have resulted in successful weight loss, it is always because the diet is not only vegan but very low in calorie density also.
Weight, is a function of energy (calorie) balance. While I would prefer for people to obtain and/or maintain a healthy weight, through a healthy diet, the reality is, a healthy weight can be obtained and/or maintained with unhealthy foods and unhealthy diets. I am sure we all know many people who have lost weight on a unhealthy animal based diet.
While at the end of the day, calories are what matter, calorie density is the real key, as it is much harder to over eat on foods that are low in calorie density. And, most foods that are low in calorie density are plant foods, like vegetables, fruits, starchy veggies, intact whole grains, and legumes. However, there are many vegan foods that are high in calorie density, such as nuts, seeds, oils, avocados, refined/processed grains, refined sugars, and all the food products made from these. Soy beans, tofu and many of the products and meat substitutes made from them can be fairly high in calorie density.
If i knew the calorie density of the two proposed diets, I would have a better chance of telling you the odds of it being successful for weight loss, otherwise there would be no way for me to know.
If you rephrased the question and proposed it as...
"do you think one would lose weight by substituting a fairly healthy vegan diet( prob. containing some soy, and meat subs, etc, but lots of plants, whole grains, fruits etc) but NOT the McD. plan that is very low in calorie density, - for a "fairly healthy" meat-eating, low-fat dairy, some sugar diet that is higher in calorie density......"
then I would be more willing to think it would, but I couldn't guarantee it.
In Health
Jeff