I think the weight issue is heavely related to gut microbe balance, the balance of good and bad microbes in gut. Here`s my wiew, i am not a weigh loss expert or diet expert either, i only read stuff about issues.
I think by modifying your gut to more ancestor like microbiota , you might better loose weigh,and also be more healthy.
I would eat a a lot cooked vegetables and some meat since both are recuired and add extra resistant starch to feed the good bacterias and maybe some extra prebiotics and psyllium , i think it takes longer time this modifying you microbiota ratios to better, by the time of 4-8 weeks of doing that you might start notice something.
Of course plain Sugar is a no no , the key is eating right type of carbohydrates that have resistant starch .
I would take also soil based organism supplement like prescript assist for example to get the "dirt" back to our body like it was when ancestors lived.