The Signs of CARB Syndrome

In my companion article on the symptoms of CARB syndrome, I covered the subjective side of the disease—what you feel and experience that no one else can directly see or measure. This article covers the other half of the diagnosis: the signs. Signs are objective indicators that can be seen, heard, felt, or measured by others—a spouse, a family member, or a clinician. That distinction matters more than it might seem, because one of the symptoms of CARB syndrome is a loss of insight and self-awareness. The person with the disease is often the last to know. The signs are how the rest of us know. The diagnosis of CARB syndrome rests on the combination: the symptoms from the inside, the signs from the outside.

1. Excess body fat, measured by body composition rather than BMI. Measure excessive body fat using actual body composition rather than body mass index (BMI). Because body composition measurements are not always available, measuring your waist-to-height ratio is useful. Divide your waist circumference by your height, using the same units for both—either inches or centimeters—and anything over 0.5 indicates excess central or abdominal fat, the type most closely associated with metabolic dysfunction. Total body obesity and central obesity are both associated with CARB syndrome. When you can’t measure body composition, simply looking at a person will give you a good sense that they have excess body fat. You won’t see well-defined muscles, because they are covered by a thick layer of fat. If you look at Mr. Atlas, you will see all the muscles because the excess fat is missing.
2. Metabolic dysfunction. Look for metabolic dysfunction. This can be assessed in several different ways. A fasting blood glucose higher than 100 is a sure sign of insulin resistance, and if it’s above 125, you likely have type 2 diabetes. HbA1c is a blood test useful for assessing insulin resistance associated with CARB syndrome. Normal is below 5.7%, and above 6.5% suggests type 2 diabetes. Glucose is only part of the picture: look at the whole metabolic cluster. Elevated triglycerides, a low HDL cholesterol, and rising blood pressure travel with CARB syndrome as part of the same insulin-resistant process.

One related laboratory check deserves a mention. Homocysteine is not part of CARB syndrome, but it damages the brain through its own pathway, and the two problems often travel together. Everyone with CARB syndrome should have their homocysteine checked, and if it is above 7 µmol/L, it should be treated with B vitamins and TMG alongside the treatment of the CARB syndrome itself.

3. Skin signs of insulin resistance. Some of the most useful signs require no laboratory at all. Acanthosis nigricans—dark, velvety patches of skin, usually at the back of the neck, in the armpits, or in the groin—is a classic visible marker of insulin resistance, as are multiple small skin tags in the same areas. You can check for these in a mirror. They don’t diagnose CARB syndrome by themselves, but when they appear alongside the symptoms, they are the body’s way of posting the metabolic problem on the outside.
4. Prolonged communication lag time (CLT). Communication lag time is a relatively newly described parameter that is a very sensitive measure of global brain function. When you engage in a conversation with another person and say something to them, within a second there is a subtle change in their facial expression that signals they have processed what you said. That means you can move on and say something else without fragmenting the communication. All of this occurs subconsciously without your being consciously aware of the process. If there were no communication lag time, you would keep piling one statement on top of another before the other party could adequately process the statements. This would make it very challenging to converse with another person who had a prolonged CLT.

Almost anyone can learn to read the subtle changes in facial expressions behind this concept. People with normal brain function know facial expressions can communicate someone’s emotional state very quickly. By looking at their facial expression, you can sense anger, concern, happiness, confusion, and other common emotions. The changes in facial expression behind the CLT concept are more subtle. The next time you communicate one-on-one with someone, pay close attention to their facial expression after you complete a statement. Look for a head nod, serial eye blinks, subtle changes in muscle movements, or mouth movements. These expressions are very subtle, so you must pay close attention and focus on them to see them. It takes practice, but most everyone can pick up on these important signals. If you know someone with a significant brain problem like dementia, major depression, or Alzheimer’s disease, look to these subtle changes in facial expression when you make a statement. Their CLT will likely be significantly longer than one second.

I first introduced this concept over ten years ago, and I noticed that in folks with normal brain function, the CLT was always less than a second. If someone has dementia or some other type of disorder that affects overall brain function, their CLT moves beyond a second. It can last longer depending on the severity of their underlying brain disorder. If you were communicating with such a person, you would likely notice that the conversation felt disjointed, even though you couldn’t pinpoint the exact reason. I have found that CLT tracks overall brain function remarkably well. I also discovered that prolonged CLT could return to normal in some situations. In my clinical experience, by far the most common cause of prolonged CLT is CARB syndrome. Unlike most brain disorders, CARB syndrome is treatable and completely reversible. As brain function improves, their CLT quickly returns to normal, as it’s a highly sensitive indicator of overall brain function. I will discuss CLT in much more depth in a separate article.

5. Psychomotor retardation or bradykinesia. This involves difficulty initiating actions, shuffling or slowed gait, reduced arm swing, or trouble with fine motor tasks like writing or buttoning. Your life seems to be moving along in slow motion, and you never seem to get up to speed regardless of your efforts. Other conditions like Parkinson’s disease, thyroid problems, dementia, stroke, and similar conditions can also cause psychomotor retardation, but they aren’t associated with the other symptoms or signs of CARB syndrome, that is, unless they have both conditions. When that happens, diagnosis and treatment options become a bit more complex. The key is to focus on the signs and symptoms of CARB syndrome. If they are present, then you clearly have CARB syndrome regardless of any other conditions. Treat the CARB syndrome, then address any remaining conditions using traditional diagnostic parameters and treatments. It’s not rocket science, but it is based on science.
6. Impaired cognition. Impaired cognition is both a sign and symptom of CARB syndrome. When it’s a sign, others notice you don’t seem as sharp as you used to be. I like the free cognitive test available on the Food for the Brain website:

I also like the Boston Cognitive Assessment (BoCA), a validated, self-administered digital test that takes under 10 minutes and evaluates global cognition across eight domains, including word list learning, memory, numerical sequences, and executive function. There are other free cognitive tests available if you simply Google “free cognitive test”.

There you have it—the signs of CARB syndrome: excess body fat that BMI can miss, metabolic dysfunction you can measure in a laboratory, the skin markings of insulin resistance, a prolonged communication lag time, slowed movement, and cognition that no longer tests where it used to. None of these signs requires the patient’s awareness to be seen, and that is precisely their value, because CARB syndrome so often hides from the person who has it. If you recognize these signs in someone you care about, you may be seeing what they cannot. And the good news stands: CARB syndrome is completely preventable and reversible with effective treatment, and as the brain recovers, the signs recede—the lag time shortens, the thinking sharpens, and the person comes back.

Frequently Asked Questions — The Signs of CARB Syndrome

1. What is the difference between a symptom and a sign? A symptom is a subjective experience you feel — pain, fatigue, cravings — that no one else can directly measure. A sign is an objective indicator that others can see, feel, or measure, like excess body fat, a lab value, or a slowed gait.
2. Why do the signs matter if I already know my symptoms? Because one of the symptoms of CARB syndrome is loss of insight and self-awareness — the person with the disease is often the last to know. The signs are how family members and clinicians know, and the diagnosis rests on symptoms and signs together.
3. My BMI is normal. Can I still have too much body fat? Yes. BMI estimates body fat from height and weight, and it misses many people who carry body fat in the obesity range at a normal weight. Body composition is the measurement that counts — and a simple waist-to-height ratio over 0.5 points to the central fat that travels with metabolic dysfunction.
4. How do I measure my waist-to-height ratio? Measure your waist circumference and divide it by your height, using the same units for both — inches or centimeters. Anything over 0.5 indicates excess central or abdominal fat.
5. What is communication lag time (CLT)? When you say something to someone, a subtle change in their facial expression within about a second signals that they have processed what you said. When that signal takes longer, the CLT is prolonged — and I have found it to be a very sensitive measure of overall brain function. In my clinical experience, the most common cause of a prolonged CLT is CARB syndrome, and it returns to normal as the brain recovers.
6. Which lab numbers point to CARB syndrome? Look at the metabolic cluster: a fasting glucose above 100, an HbA1c of 5.7% or higher, elevated triglycerides, a low HDL cholesterol, and rising blood pressure — all part of the same insulin-resistant process.
7. Should I have my homocysteine checked? Yes. Homocysteine is not part of CARB syndrome, but it damages the brain through its own pathway and the two often travel together. If yours is above 7 µmol/L, it should be treated with B vitamins and TMG alongside the CARB syndrome treatment.
   8. How can cognition be tested objectively? Others often notice first that you don’t seem as sharp as you used to be. For a measurement, I like the free cognitive test on the Food for the Brain website and the Boston Cognitive Assessment (BoCA), a validated self-administered test that takes under 10 minutes.