I've been thinking a lot lately about all that's been reported about weightloss, low-carb, low-fat, and calorie restriction and I've come up with my theory about why it's necessary for some of us to go very low-carb and others can tolerate higher-carb levels and why some of us need to cut calories to lose weight and others can eat higher-amounts and still lose weight. A lot of this is based on reading your comments on this forum and my own experiences.

Insulin Resistance

1. When a person is Isulin Resistant (IR), their body gets used to producing excess insulin to process glucose. The longer a person is IR, the more their body gets used to over-producing insulin, which eventually leads to diabetes by burning out their pancreas.
2. Even though a person can become Insulin Sensitive (IS) through low-carbing, their body continues to over-produce insulin to a certain degree.
3. Therefore, a person's level and length of IR directly affects how well they process macronutrients, especially carbs, even when they become IS. (Note: Over-production of insulin may eventually dissipate, but I think it takes a proportionately long time compared to the amount of time you were IR. For me, I've been IR for probably 35+ years, I've got a lot to make up for.)

Part of my reasoning for this is my reaction to low-cal. I've been having some trouble with low-bloodsugar since going low-cal. Since my body no longer has the extra fat to move into fat cells with the excess insulin I'm creating, it's over-cleaning my blood of glucose. This happens in particular before lunch. At breakfast, I have about 30 grams of carbs, about 3/4 of my current daily intake. I'm contemplating moving my paleolithic punch to dinner to help alleviate this.

Weightgain

1. Because a person who has been IR is over-producing insulin, they are more sensitive to a smaller amount of carbs.
2. The insulin is then used to process not only the carbs (glucose) but the excess can be used to move some or all of the unused fat into fat cells -- it does not convert that fat for energy, that's a different process not driven by insulin.
3. So, even though a person who has been IR might be eating what would normally be considered a reasonably low amount of carbs (say 60 grams -- differs for each individual), if they eat more calories in the form of fat and carbs than they need to meet their energy needs, they will gain weight. This person may never have a high tolerance for carbs.
4. On the other hand, the person who was never IR or not long enough to affect their insulin production permanently, will produce just enough insulin to process the carbs they eat and excess fat calories will be passed through their system and not go toward weightgain. (Note: If they do eat enough carbs to exceed their energy needs, the excess carbs will still be stored as fat, so even they are not immune from weightgain ) I think IS people will also tend to be in better shape than those of us who have been IR for a long time and have higher metabolisms, which will increase their basic calorie needs, so they will be able to eat more calories and still lose weight.

My experience has been that upping my carbs to about 80 a day and eating way too many calories caused me to gain weight in the last eight months or so (about a pound a month), even though I thought I was being a very good low-carber.

Weightloss

1. A person's basic calorie needs change with age, size, activity, macronutrient ratios and X (the unknown variable ). I think it's impossible with current tests to determine accurately what a person's basic calorie needs are.
2. When a person low-carbs, they remove or inibit insulin's role in the weightloss calculation.
3. Because we cannot accurately determine what our basic calorie needs are, we use tools that hopefully come close to a good ballpark value for us as individuals to use as guides in our endeavours to control our weight.
4. Because our bodies use fat and protein as building blocks, not all of the calories in are utilized as calories. In addition, it takes more energy to process fat and protein for energy than it does to process carbs. Thus my explanation of the "metabolic advantage."
5. Therefore, it is possible to ingest more calories than needed and still lose weight if you are eating low-carb. But calories still count -- just not as much.
6. However, because of the "metabolic advantage," it's possible to eat enough calories to keep your body from going into "starvation mode" and provide continued weightloss.

Again, my experience: As soon as I cut my calories to between 1600 and 1800 a day, with a 2000 cap, I started losing weight again. I'm going to keep to this level until I get where I want to be and then go back to maintenance-level, for me, low-carb.

So, there you have it. Tear it apart, please. I'm very curious as to your views.