Ideally no. The concern I have with soy(a) milk is much more about health, than weight. It is made by soaking dry soybeans and grinding them with water. Soybeans are one of the biotech crops, which have been genetically modified. More than 60% of processed foods contain soy(a) in some form – it can be found in anything from processed cheese to pet food or from noodles to hydrogenated oils. Soy(a) in its various forms doesn’t pass the basic ‘real food’ rule of The Harcombe Diet.
If you are intolerant to milk, either avoid it altogether or try raw (unpasteurised) milk. Many people find that they can tolerate milk that hasn’t been ‘food processed’ at all. Try milk from different animals e.g. sheep’s or goat’s milk, if you think that it may just be cow’s milk that causes you problems.
If you are still keen to consider a non-animal option, almond milk would be better than soy(a) milk and so would rice milk. I would recommend reading the soy information on the www.westonaprice.org website and then you may choose to avoid soy products.