I also went to the lab last Thursday as it was time for my semiannual visit to the endo, which gave me more insight into what changes the diet had made in my health.
Nutritional Breakdown
Here is what I ate during the second week of my diet. As you can see it was only slightly higher than the intake the previous week. Salt was well controlled and protein was slightly higher than recommended for someone on a long term low carb diet, but lower than that for someone not at all adapted to ketosis*:
Impact on Weight
I had set my calories at the brutally low level that the nutritional calculator predicted should yield a weight loss of 1 lb a week. The level was low because I am old and short, and because I started out at a normal weight. Since it only takes about 1,560 calories to maintain my current weight, the nutritional theories I lay out in my Diet 101 book, which are embodied in the calculator, predict I would have to eat no more than 1,060 calories a day for a week to lose a pound of real fat.
Before starting the diet my weight had been hovering around 146.5 lbs, however, it was 148 lbs the day I started the diet thanks to the very salty Vietnamese lunch I'd had the day before with it's miso-based soup and soy-sauce based sauce. I always gain 2 or 3 lbs after eating a soy-sauce laden meal.
My weight on Monday morning after 2 weeks on my diet was 141.2. This was a loss of scale weight of 6.8 pounds, but because I was eating less than 20 grams of carbs all week, I knew that a good 3 lbs or more of my weight loss was due to the loss of glycogen, which is the substance our body uses to store glucose in both our livers and our muscles. (Details about glycogen-related weight loss HERE.)
I had stopped taking my metformin in the middle of the first week as metformin does interesting things to glycogen and I wanted my diet trial to be cleaner. So after 10 days without metformin and 14 without carbs, I figured I'd probably flushed out as much glycogen as I was going to lose. In the past that was usually about 3 lbs.
Since glycogen comes back as soon as you raise your carbs I expected to see the 3 lbs come back within a few days after ending my diet and raising my carbs back to their usual level which is around 100 g a day.
I also expected that some of my weight loss was due to the fact that since I was eating so little to meet my caloric goal there was less weight of food in my stomach and gut. That too would come back.
Since this past Monday, I have started using metformin again and eating about 100 grams of carbs a day, while eating a maintenance diet. My glycogen is probably as refilled as it's going to get. My weight this morning was 144.6. This is almost exactly 2 lbs less than my average weight during the weeks before I started the diet.
This confirms that my nutritional calculator does a good job of predicting weight loss and, most importantly, that there is no "metabolic advantage" for me in eating a very low carb diet. I did not lose any more weight than would be predicted by caloric deficit.
Had I been in a study, however, my specious loss of 6.8 lbs might have made it look like there was an advantage to eating a very low carb diet since low fat diets don't always flush out glycogen and the food may weigh more.
Unfortunately, it looks like, as usual, the weight came off my face and neck which look more wrinkly and stringy than usual. My tummy, which is the only place I carry significant amounts of subcutaneous fat, doesn't seem any smaller. The Tanita readings are fluctuating so much that I'll have to wait another week or so to see if they show any substantive loss of body fat percentage.
Blood Pressure
My two week diet was designed to be low in salt, because it is too easy to eat a lot of salt while eating a classic LC diet and I have issues with my blood pressure. I bought low salt cold cuts without preservatives at Trader Joe's and stuck with cheeses that were lower in salt, too. No pork rinds or other salty low carb snacks!
My blood pressure was all over the place during my diet, high and normal an then high again. When I started to cautiously supplement with potassium chloride (in the form of Morton's Not Salt) it dropped to completely normal and stayed that way for the last few days of the diet.
I was supplementing with the potassium because I get leg cramps and palpitations when I eat very low carb without potassium. This is because flushing out glycogen also triggers a loss of potassium. (This loss is measured in some studies as a rough gauge of how much glycogen has been lost.)
My lab results from last Wednesday when my blood pressure was 122/73 showed that my blood sodium level was at the very bottom of the normal range and potassium was in the middle of the normal range. This was reassuring, as I had a concern that the Captopril I take might cause my potassium levels to rise too high. I was not dehydrated, based on my normal BUN. In the past when eating LC I have almost always had a high BUN. Controlling protein might have helped there as did the potassium.
When I ended my diet and went back to eating normally, my blood pressure soared. As a further experiment I went back to supplementing with potassium, thanks to the suggestion one of you sent me, and today my blood pressure is back to being normal, at 114/74, as opposed to the 151/92 it was three days ago.
Since I had a lot of trouble with very high blood pressure while eating a very low carb diet in the past--the exact opposite of what the LC gurus claim happens--I'm starting to think that BP for me is all about those potassium levels. Low carb diets can be very high in sodium and potassium deficient, and that may be why I had so much trouble with blood pressure eating a long-term low carb diet.
Blood Sugar
My blood sugars had continued to be beautiful--in the 70s and low 80s at all times. So it was daunting to discover that the lab said my blood sugar was 92 mg/dl when my meter said it was 83 mg/dl. This means that the FreeStyle Lite meter that my insurer forces me to use reads low. So it's probable that my 70s were really 80s and 80s were 90s. It also means my occasional 140s were probably really 150s.
My A1c was 5.5%, which is .2% lower than usual. Some of the drop is due to the low carbing I'd done during the previous 2 weeks. Though doctors think that the A1c reflects the control of the last 3 months, this is not entirely true. The A1c most strongly reflects the blood sugar control during the previous 2 weeks, with the rest of the past experience only making a smaller contribution.
My A1cs are always higher than predicted by my average meter readings, and this one is no different. I attribute this to the likelihood that my red blood cells are living longer than average which will raise how much glucose has become bonded to them. It is that, not actual blood sugar levels, that the A1c measures.
Mood and Energy
By the end of my diet I felt like absolute crap. I wasn't sleeping well and was having the vibrant dreams that happen early on in a ketogenic diet, but there was no sign of the energy burst I usually experience at that phase of an low carb diet. This may be a result of how low my calories had to be for me to lose weight.
Whatever the explanation, I felt exhausted and depressed, and just walking around was a challenge. As soon as my diet was complete and I raised my carbs back to their usual level I felt like my old self with much better energy.
I was very hungry throughout the last week, too, even though my fat intake was reasonably high and my blood sugars completely flat.
Because my blood sugars are very well controlled right now I did not get into binging once I stopped my diet and started eating carbs again. In fact, I had a couple days when I was very busy with a new project over the past few days where I didn't end up eating all that much. This verified my belief that, for me, when I am eating carbs, hunger is entirely about how high my blood sugars surge. Right now they aren't surging very high even when I eat 20-30 g of carbs per meal, so I'm not experiencing blood sugar-caused hunger.
In the past eating a very low carb diet for a few weeks has given me decent energy and no hunger, but I wasn't limiting calories. However, throughout the past 5 years when I've done a very low carb diet not counting calories, I haven't lost an ounce of real weight.
Miscellaneous Observations
I ended up having a lot of heartburn on this diet. Peanut butter and Greek yogurt both caused it. Cheese did not (ruling out that I'm sensitive to dairy, per se.) When I went back to eating gluten at the end of the diet I did not experience heartburn. There doesn't seem to be any reason for me to go gluten free.
Conclusions
Calories count. My nutritional calculator is pretty accurate. It is extremely hard to find low carb foods that meet the caloric target I have to hit to lose weight without boosting protein too high.
This diet confirmed that for me to lose any weight at my age (64) and size (5' 3 and 144 lbs) I'd have to eat no more than 1250 calories a day to lose 2 lbs a month, even on a low carb diet, which for me would be an unsustainable starvation diet.
So my conclusion is that my weight loss diet days are over and that now that I'm heading into my misnamed "golden years" I better get used to carrying a bit more weight because the alternative is a starvation lifestyle.
Fortunately, there is a solid body of research suggesting that the healthiest weight for people my age and older skews towards the "overweight" category (BMI of 25 and a bit higher).
What this may mean for you is that the time to lose weight is when you are in your 30s, 40s, and 50s, when you burn more calories just breathing and walking around. Our metabolic rate drops with each decade we survive--even with exercise--so it gets tougher to lose weight as we get older.
Low carb diets are very effective for people with a lot of weight to lose whose caloric needs are much higher, but their main advantage in respect to weight loss is that when people cut out carbs they cut out all the high caloric junk that is what caused them to gain weight in the first place. If you control protein it becomes much tougher to overeat on a low carb diet, too.
The true virtue of low carb diets is, of course, that they control blood sugar very well. If my current blood sugar-control regimen stops working, I know that cutting back on carbs will drop my blood sugar (as long as I have functional beta cells, which fortunately, seems to be the case.)
Comments?
NOTE: In response to a point brought up in one of the comments it's worth noting that after Thanksgiving I did 10 days of a classic "Don't count anything but carbs" diet. In contrast to what happened with the calorie controlled low carb diet described above, I lost a grand total of 2 lbs during the "all you can eat" LC diet which came back when I raised carbs out of the ketogenic range. I was spilling urinary ketones from day 3 to day 10. Blood sugar and blood pressure were normal on that diet (after a rocky first few days for the blood pressure, again) but as has been the case for me for the past 5 years, a ketogenic low carb diet without caloric restriction is worthless for weight loss.
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* I used the body fat percentage my Tanita scale provides when using the calculator to estimate intake. If I omitted the body fat percentage, the calculator would tell me that I would have to eat a starvation diet to lose 1 lb a week, which it won't provide numbers for.
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