Insulin levels, for example are affected not only by what you eat, but also your stress levels. Remember back to the HPA Axis, when stress goes up, the body releases cortisol which triggers the release of blood sugar—-which triggers the release of insulin. This is why people with diabetes not only have to watch what they eat, but also their stress levels. Some feeding programs like Eat Stop Eat which promote intermittent fasting work for some people, but if you are stressing about when you can eat again, you are likely increasing your cortisol/blood sugar/insulin and defeating yourself anyway. New eating patterns take a couple of weeks to take effect, but after that, if you are miserable, you will not stick with it in the long term, and you are increasing your stress levels…. try something different (unless it is a medical thing).
Hormone levels also impact the way your body responds to meals. When women are nursing, they “naturally” store more fat as reserve to help make milk. If you diet while you are nursing, you are risking a significant reduction in your milk, and it seems like it is a futile effort anyway.
Stress also causes the body to store fat around the belly. even in people who do not “stress eat,” to the theory that the only reason people gain weight when they are stressed is due to overeating is debunked.
What's my point? Healthy nutrition is a lifetime process. It involves managing stress, eating relatively healthfully and knowing your body. Find a healthy program that works for you. For most people, eating from at least 3 food groups at each meal, and drinking at least 80 ounces of water (4 bottles isn't that hard) helps. If you feel better eating several small meals and are not packing on the pounds, then that might work better for you, especially if you give your body a 12-hour break between dinner and breakfast. There are dozens of different eating programs out there. Seek consultation with your doctor or a Registered Dietician for help finding one that will meet your individual needs. (Side note: In nearly all states it is ILLEGAL for someone who is not a physician or registered dietician to design a meal plan for you and give you nutritional prescriptions. They can educate you about things like insulin, healthy eating etc, but they can not tell you what you need to eat.)
This is not medical advice. I am just pointing out some common sense facts. What works for your husband, or your sister may not work for you. It doesn't mean you are a failure. Weight maintenance is far more complex than just calories in vs. calories out, regulating insulin or reducing carbs. Keep a journal with MEASUREMENTS or get a fat caliper to measure body fat percentage. Your weight can fluctuate up to 5 pounds each day, and the body fat scales can fluctuate up to 3% based on your hydration levels. Go old school. Find a program that is slow and steady that you can do for life without feeling deprived or miserable. Make sure to keep track not only of what you eat, but also your mood, energy level, stress level and quality of sleep. (And women, add information about your monthly cycle). This can help your care team help you.
Finally, consider the reasons you want to lose weight. If you have low energy and depression, monitor those things with each eating program. If, over a month, they improve, you are probably on the right track. If you get more stressed or unhappy, re-evaluate.
https://www.holtorfmed.com/stress-cortisol-insulin-resistance/
https://www.womentowomen.com/insulin-resistance/insulin-resistance-what-is-it-and-how-we-can-heal/
https://www.womentowomen.com/healthy-weight/weight-loss-and-adrenal-stress-2/
https://draxe.com/intermittent-fasting-benefits/
https://draxe.com/intermittent-fasting-women/