So the theory goes: high carb meal -> blood glucose spike -> insulin spikes a little too hard -> hypoglycemia -> hunger, so you eat to replenish blood glucose.
In the original theory of hangry, hypoglycemia was a core component, although as Jane Plain pointed out, it could be the relative, not absolute levels of blood glucose that count (&/or free fatty acids, but that’s a story for another day). This could be true, in part because:
1) symptoms of hypoglycemia rarely correlate with actual hypoglycemia;
2) many episodes of actual hypoglycemia are asymptomatic; and
3) hunger isn’t even one of the main symptoms of hypoglycemia.
Tl;dr: hangry might be a real phenomenon, but there are little/no data to support it, and much to the contrary.
The low carb brigade says “LCHF = no hangry.”
Turns out, the same can be said by the high carb brigade (in some contexts), so does it really matter? (see below)
What we know: obese insulin resistant patients undergo a spontaneous reduction in appetite upon initiating a carbohydrate-restricted diet. FACT (P<0.05). Low carb, high protein meals also induce more satiety than high carb meals in acute scenarios…
Imho, hunger and satiety are complicated biological phenomena that can’t be so easily simplified into cute concepts like “hangry.”
Overweight/obese, single meal study
Reducing the glycemic index or carbohydrate content of mixed meals reduces postprandial glycemia and insulinemia over the entire day but does not affect satiety (Liu et al., 2012)
[protein and calories were constant]
“There were no significant differences in ratings of hunger, fullness, or satiety between the different dietary treatments.”
Type 2 diabetic patients, single meal study
A high-glycemic index, low-fiber breakfast affects the postprandial plasma glucose, insulin, and ghrelin responses of patients with type 2 diabetes in a randomized clinical trial (Silva et al., 2015)
“Subjective satiety did not differ between breakfasts.”
Overweight but otherwise healthy, single meal study
Return of hunger following a relatively high carbohydrate breakfast is associated with earlier recorded glucose peak and nadir (Chandler-Laney et al., 2014)
This is the study most cited in support of hangry. Problem is, it doesn’t really support the concept.
note: glucose nadir >90 mg/dL (ie, not really “low”)
Hunger was a bit higher in the high carb group, and fullness was unaffected:
Here’s what the authors had to say about it:
Overweight/obese, 6 month study
Effect of the glycemic index of the diet on weight loss, modulation of satiety, inflammation and other metabolic risk factors: a randomized controlled trial (Juanola-Falgarona et al., 2014)
“Despite this tendency for a greater improvement with a low-GI diet, the 3 intervention groups were not observed to have different effects on hunger, satiety…”
Effect of dietary carbohydrate, fat, and protein on postprandial glycemia and energy intake in cats (Farrow et al., 2013)
“High-carbohydrate diets increase postprandial glycemia in healthy cats compared with diets high in fat or protein, although energy intake is lower.”
They probably ate less because it wasn’t meat (maybe [although this goes against the protein leverage hypothesis (I think)]), but it still doesn’t entirely jive w/ hangry.
PROTEIN: Normal weight/overweight/ obese kids, single meal study
Breakfasts higher in protein increase postprandial energy expenditure, increase fat oxidation, and reduce hunger in overweight children from 8 to 12 years of age (Baum et al., 2015)
“All participants had decreased feelings of hunger and increased fullness after the PRO than the CHO.”
a ha! worded another way, this could be interpreted as kids who ate carbs for breakfast got hangry and ate more at lunch…
However, “There was no effect of breakfast type or body weight over time for blood glucose.”
There are definitely more studies out there, some that even show correlations between postprandial hypoglycemia and hunger, but there are a lot that don’t. I’ve actually seen studies that seemingly do support some models of hangry, albeit in an abstract way; eg, healthy participants jabbed with insulin in the middle of the night spontaneously eat more at breakfast… but these are artificial experimental conditions, not after “people just eating food.”
There are plenty of ‘good’ reasons to advocate low carb diets; but “LCHF = no hangry” and “LCHF = effortless fasting” just aren’t them.