Why Weight Loss Stops on Long Term Low Carb Diets

The enthusiasm for the low carb diet as a weight loss diet arises in the first few weeks and months when most people experience dramatic weight loss.

What rarely gets mentioned--especially in the miracle weight loss books--is that very few low carb dieters ever get to their weight loss goal, especially those who start out with a lot of weight to lose.

I am enthusiastic about the power of carb restriction to lower blood sugar to normal or near normal levels. I am not as enthusiastic about low carbohydrate dieting as the solution to tough weight loss problems.

Because even the online low carb community tends to believe that people who stall out are "not doing the diet right" and respond to stall posts with that assumption, most people who do stall out long term leave the discussion boards, leaving only those who have succeeded to greet the newbies.

But as someone who stalled out for years on my own weight loss, and someone who has read the boards for years, I am convinced that permanent stalls are the norm and the people who get down to goal the exception--especially among those older than 45.

In this post I'm going to discuss a few reasons why this happens.

1. Thyroid slowing. Long term low carbing causes changes in T3 hormone levels which are often hard to diagnose. It can cause something called "Euthyroid syndrome." I learned about this from Lyle Macdonald's book, The Ketogenic Diet, which has cites to the relevant research. Getting help for this problem is very hard as your TSH will be fine and standard thyroid testing may not pick it up.

Physiologically what seems to happen is that your body responds to months of ketogenic dieting by assuming you are starving--people who are starving are in ketosis all the time too. So it turns down the thermostat to conserve your body mass so you don't die. If this happens to you you'll know it. You'll feel exhausted and dragged out all the time, and the burst of energy most people feel when they start out low carbing will be a distant memory.

Dr. Bernstein reports that many of his patients develop thyroid problems months after starting the LC diet, but he insists this is because they have developed autoimmune thyroid disease. I have to question this. Too many of us with no markers for any kind of autoimmune disease experience this metabolic slowdown on long term low carb diets. Whatever the explanation, once your thyroid slows, you weight loss will slow dramatically.

My take on this now is that it is a good idea to raise your carbohydrate intake over the ketogenic boundary from time to time. Where that boundary is varies from person to person. It's the point where after adding a few more grams of carbohydrate to your intake, you suddenly gain the 3-8 lbs you lost the first three days you were on the diet. That instant weight gain is not fat. It is the weight of the glycogen you've just restored to your liver and muscles.

Watch your calories closely when you raise your carbs this way and you shouldn't gain any weight. In fact if you watch calories and keep carbs just over the boundary while lowering your fat intake you might lose a pound or two.

Note: If you can't keep your blood sugar normal at an intake high enough to get you out of a ketogenic state it might be time to talk to an endocrinologist about safe drugs that can help. I personally maintain now at an intake that varies from 70-110 grams a day (my ketogenic boundary is at about 65 grams a day.) If I stay lower than 50 for six weeks I always develop that half dead feeling again. I need insulin at some of my meals to eat at this level, but I feel a lot better when I do. Metformin along with the insulin keeps me from gaining weight. In fact, I have been losing slowly and steadily over the past six months with the combination of lower fat/higher carbs, insulin and metformin.

2. Fat-induced insulin resistance. There is some interesting research that has been discussed on the Whole Health Source Blog about how, and more importantly, why, palmitic acid, a saturated fat might raise insulin resistance in rodents. There are a lot of other studies over the years that have demonstrated that high saturated fat intakes of all kinds increase insulin resistance too.

While I don't believe that high sat fat intake worsens heart disease or cholesterol, I think it is very possible that, for the reasons that Stephan Guyenet hypothesizes in the Whole Health Source post, long term high saturated fat intake does does increase insulin resistance, and that after many months of eating very high fat/low carb diets this increase in IR can become a huge problem especially when people experience "carb creep."

"Carb creep" is very common. Over time most of us end up eating more carbs than we think we do. A bit more here, a bit there, or perhaps we are eating larger portions of lower carb foods than we realize, so that 4 g intake is 8 g. Do that five times a day and you are eating a lot more carbs than you realize.

The cure for this is to weigh your portions for a while and get accurate carb counts. If you are eating over 60 grams a day, cut back on the saturated fat and see if that helps. I am starting to think the very high fat low carb diet is only appropriate with extremely low carb intake levels.

For those of us eating low carb to control blood sugar, a higher carb intake may be necessary to keep ourselves from experiencing diet burn out. If your blood sugar is under control at a higher carb intake, your health is fine. You may have to compromise on weight loss, though. Or perhaps cut back on the cheese, butter, nuts, meat fat and cream and see if cutting out some of that saturated fat helps.

3. Stalling Is Built Into the System. The 10% factor. High quality research which I've blogged about elsewhere suggests that when people have lost between 10-20% of their starting body weight they will experience metabolic slowdown no matter what diet they use.

When I polled the diabetes community last year about their own diet experiences, the single most often repeated report was that most people who cut carbs could lose and maintain the loss of 20% of their starting weight, but after that, forget it. This is better than Dr. Leibel's results with a mixed diet, where slowdown kicked in at 10%, but it's far less weight loss than most people who embark on a low carb diet hope to lose.

My belief is that if you stall the smartest thing you can do is declare victory and maintain your weight for a few months without attempting to lose more. Make your body feel safe, so your thyroid ramps up a bit and stops worrying about the next famine. If you can't maintain at your partial weight loss, you are not going to be able to maintain if you lose more.

In fact, the sanest goal would be to find the weight level at which you can maintain happily without feelings of deprivation and stay at that weight. Then you might just not become one of the many many low carb dieters who lose 100 lbs and gain back 120. There are far too many of them, most of them blaming themselves for weakness. My guess is it isn't weakness, it's the revenge of a metabolism that has been pushed too far and is now 100% dedicated to preparing you for the next massive famine.

4. Calories Do Count. There is a glorious period when people start their first low carb diet where they do seem to trick the body into dropping crazy amounts of real fat--despite eating relatively high calorie intakes. This passes. Oh, how it passes.

Once you have dropped that initial 10% or so the magic of low carb dieting wears off and the only way most of us (not all, but most) lose any more weight is by cutting back on our food intake.

To lose weight you do have to cut calories below some level which for many of us with metabolic problems or who are older is MUCH lower than what dietitians tell you or what you get when you use online calculators.

After years of thinking I couldn't lose weight cutting calories, I learned I can--thanks to a week long attack of stomach poisoning. It turns out all I have to do is cut my calories down to about 800 a day and I will lose. The calculators tell me I should lose on 1350. The nutritionist told me I should lose on even more than that. Twice this year I've been sick for a week unable to eat and both times I have lost a pound or so eating 800 calories--and most significantly, kept it off later on.

Do I want to keep eating like that to lose more? No. Because if there is one thing I've learned, it is that you maintain your weight loss on a diet only a few hundred calories higher than the one you ate while losing. I have no wish to have to eat 1,000 calories a day for the rest of my life.

Normal Blood Sugar Is The Best Goal To Chase. Most of us started obsessing about weight loss because doctors told us if we lost a lot of weight we'd stop being diabetic. This is absolute hogwash. Go look at my Type 2 Poll if you still believe this. It isn't the weight loss that controls blood sugar it is cutting out the carbs. No matter how thin we get, most of us will see diabetic blood sugars if we eat carbs.

If you understand this, but also understand that maintaining normal blood sugars no matter what you weigh will eliminate diabetic complications including heart disease, you should be able to accept whatever weight loss you can achieve and relax about the rest.

Carb restriction is a powerful tool for achieving normal health. It's a useful approach to weight loss, but like ALL diet approaches, it only goes so far. Yes, there are people who have huge low carb weight loss successes, but for every one of those there are hundreds who stall out at that 20% lost from starting weight. If you can get to even 15% lost, give yourself a big pat on the back, realize you are are normal if you stall, and get to work on maintaining that impressive weight loss for life.