I can absolutely relate to what you describe, including the secretive side. In my case I have also got a history of restrictive patterns of eating, and fluctuated between the two extremes, so we are not in exactly the same position, but I wanted you to know I do understand.
For me there has been no magic bullet but over the past five or so years things have improved a lot. It is something I had been actively trying to address for over ten years before that, and had been suffering with for several further years before that.
I’m not sure exactly what helped most in my case but I think a combination of:
therapy - for food but also general, for self
seeing a nutritionist (not helpful at the time so much but helpful in retrospect re: making good meal choices once in a position to do that).
regular exercise including a muscle building component. E.g. weights, reformer Pilates, martial arts
yoga most days.
eating a lower carb/Mediterranean diet and ensuring all carbs are taken with protein too.
The book “brain over binge” did help, I think. It offers a bit of empowerment as well as an explanation for thinking patterns that helps you “check yourself” in the moment. For instance, when smelling something like freshly baked cookies I might previously have bought a packet or three to binge on, whereas the book taught me that was just my “lizard (primitive) brain” response and I could overcome that with rationalisation.
Escaping from a toxic and abusive relationship. (Not saying this applies to you but perhaps there are difficulties in your life that you could seek to cast off or mitigate)
Try to make healthy meal choices even if you binge over and above that. You’ll likely have both a physiological and a psychological addiction; better food will help your body physiologically and I hope, in time, psychologically.
(Keto was also helpful. Intermittent fasting, however, was a disaster in terms of binge relapses, though now I would probably have the confidence to tentatively try it again at some point.)
The “sunk costs” fallacy. Once I had bought food, if I started bingeing but was then able to think myself out of continuing, I would chuck the food away (destroyed/rendered inedible if risk of retrieving later). You’ve spent the money either way and aren’t going to get the money back if you eat the rest of the food rather than chucking it. So it’s not a waste and it’s better for your body.
I am now a healthy weight that doesn’t fluctuate much, have a lot of energy, eat healthily but not obsessively and have far fewer urges to binge which I can resist 99 percent of the time.
I have been a healthy weight at other points before when simultaneously desperately unwell with disordered thought processes and behaviours around food, so the weight is not a benchmark for me but rather how I feel and behave.
I think the combination of all of the above suggestions (and time) has made this, tentatively, feel different for months to perhaps even years. I would not say I am cured but am feeling the best I’ve ever felt, and have been for a sustained length of time.
You might like to get a free trial of one of those blood sugar monitors (freestyle) which will give you data about how different foods (including sugar and carbs) affect your blood sugar. You could then read about how blood sugar affects body and mind.
very best of luck. I do think this is something you can tackle, and I do understand. I could weep when I think of the money I have wasted on junk food over the years and the time I have lost to it. It’s a horrible addiction.