There exists a theory that could explain why sometimes after eating a meal your blood glucose levels may rise higher than normal.
It’s called the Chinese Restaurant Effect. And while it is only a theory, some science exists that could back it up.
A moment of clarity
Before we look at what the Chinese Restaurant Effect is, let’s just clarify what it is not. It is not what has been referred to as Chinese Restaurant Syndrome (CRS). CRS refers to when people experience symptoms such as sweating and headaches after eating in Chinese restaurants. Doctors now call this the MSG effect (effect of monosodium glutamate), an additive used in restaurants and pre-packaged foods.
There’s more to the MSG effect than just those three sentences, but I won’t digress any further.
What is the theory?
The Chinese Restaurant Effect was coined by low carb pioneer Dr Richard K Bernstein.
Dr Bernstein has spent much of his professional life battling out of date theories about diabetes. Now aged 85, he attributes his excellent type 1 diabetes management to a low carb diet.
It was in 1997 that Dr Bernstein released his seminal book Diabetes Solution, where he describes a conversation with a patient who experienced dramatic blood glucose increases whenever she went swimming.
A real food enthusiast for the ages, the woman ate a head of lettuce prior to any time she swam. Lettuce heads contain around 10g of carbohydrate, with Bernstein writing that this would likely raise the blood glucose of an adult with type 1 diabetes by 2.8 mmol/L at most.
So why did her blood glucose climb from 5.0 to 16.7 mmol/L? This, Dr Bernstein says, can be explained by the Chinese Restaurant effect.
How does the Chinese Restaurant Effect work?
Chinese meals often contain protein or slow-acting low carb foods such as bean sprouts, bok choy, mushrooms, bamboo shoots and water chestnuts. When eaten in large amounts, as they often are in an all-you-can-eat buffet setting, Dr Bernstein says a funny thing happens:
“The upper part of the small intestine contains cells that release hormones into the bloodstream whenever they are stretched, as after a large meal. These hormones signal the pancreas to produce insulin in order to prevent the blood sugar rise that might otherwise follow digestion of a meal. Large meals will cause greater stretching of the intestinal cells, which in turn will secrete proportionately larger amounts of these hormones.”
However, in people with diabetes, insulin isn’t produced (as is the case with type 1 diabetes) or doesn’t work properly (as with type 2 diabetes).
Glucagon is another hormone, which raises blood sugar levels. It achieves this by telling the liver to make new glucose. Glucagon, under normal conditions, counters the glucose-lowering effects of insulin, and this system helps to to regulate blood sugars throughout the day. In diabetes, half of this system may not be running properly.
Dr Bernstein opined that eating large amounts of food could trigger a disproportionate glucagon response, especially in people with diabetes:
“Since a very small amount of insulin released by the pancreas can cause a large drop in blood sugar, the pancreas simultaneously produces the less potent hormone glucagon to offset the potential excess effect of the insulin.
“If you’re diabetic and deficient in producing insulin, you might not be able to release insulin, but you will still release glucagon, which will […] thereby raise your blood sugar.
“Thus, if you eat enough to feel stuffed, your blood sugar can go up by a large amount even if you eat something indigestible, such as sawdust.”
So…is it real?
There is some science to suggest that the Chinese Restaurant Effect could exist.
In 2016 US researchers reported on sensory neurons that detect when the stomach stretches in the digestive system. They addressed a study by Chambers at al. in 2013 which claimed that after a sizeable intake of nutrients, “enteroendocrine cells respond by releasing a myriad of gut hormones, including serotonin, glucagon-like peptide 1 (GLP1), cholecystokinin, peptide YY, and others.” [1]
There’s a lot of heavy science in there, but it basically backs up that glucagon is released following consumption of food.
In the same year, Harvard added weight to the theory. A Harvard Medical School study reported, “The neurons that sense stretch in the stomach produce receptors for glucagon-like peptide 1 (GLP-1), a hormone released from the intestine in response to the arrival of nutrients.”
What does it mean for me?
People with diabetes who experience higher than normal blood sugar readings following food may want to revisit the food they ate. Did you eat more than you normally would, even if it was low carb?
Eating smaller portions of food is better for us than eating too much. So whether or not the Chinese Restaurant Effect is ever disproven, the reasoning behind Dr Bernstein’s hypothesis is pretty sound.
However, it remains a theory. And there could be any number of reasons for someone’s blood glucose spiking unpredictably after eating food: responses to medication, exercise, stress, adrenaline or anxiety, or delayed food response from earlier in the day.
Ultimately though, eating low carb will help to keep blood glucose levels down. And eating reasonable portion sizes is more tailored to healthier blood sugar control.
[1] Cell. 2016. Sensory neurons that detect stretch and nutrients in the digestive system. [ONLINE] Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4930427/. [Accessed 20 June 2019].
