The Effect of Low-Carbohydrate Diet on Macrovascular and Microvascular Endothelial Function is Not Affected by the Provision of Caloric Restriction in Women with Obesity: A Randomized Study.
Study Goal
The researchers aimed to determine whether a low-carbohydrate diet, with or without caloric restriction, improves macro- and microvascular endothelial function in women with obesity.
Results Summary
The study found that a 6-week low-carbohydrate diet, regardless of caloric restriction, improved microvascular endothelial function via increased nitric oxide bioavailability but did not affect macrovascular endothelial function.
Population
21 healthy women with obesity (BMI: 33.0 ± 0.6 kg/m², age: 33 ± 2 years).
Effective Dosage
~10% carbohydrate calories (with or without a 500-calorie/day deficit).
Duration
6 weeks.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
low-carbohydrate (LC) diet without caloric restriction (CR) | increase | macro- and microvascular endothelial function | women with obesity | - | would improve | #1 |
low-carbohydrate (LC) diet with caloric restriction (CR) | no change | macro- and microvascular endothelial function | women with obesity | - | would not improve | #2 |
6-week LC diet with CR | no change | macrovascular endothelial function, measured as brachial artery flow-mediated dilation | women with obesity | 7.3 ± 0.9% to 8.0 ± 1.1% | did not change | #3 |
6-week LC diet intervention, regardless of CR | decrease | microvascular endothelial function, measured by arteriolar flow-induced dilation | women with obesity | - | decreased | #4 |
6-week LC diet intervention, regardless of CR | increase | decrease in microvascular endothelial function after blocking nitric oxide production | women with obesity | - | the magnitude was more than baseline | #5 |
6-week LC diet, regardless of CR | increase | microvascular endothelial function | women with obesity | - | may improve | #6 |
6-week LC diet, regardless of CR | no change | macrovascular endothelial function | women with obesity | - | may not improve | #7 |
6-week LC diet, regardless of CR | increase | NO contributions | women with obesity | - | improved | #8 |
6-week LC diet, regardless of CR | increase | bioavailability of nitric oxide | women with obesity | - | increasing | #9 |
Obesity impairs both macro- and microvascular endothelial function due to decreased bioavailability of nitric oxide. Current evidence on the effect of low-carbohydrate (LC) diet on endothelial function is conflicting and confounded by the provision of caloric restriction (CR). We tested the hypothesis that LC without CR diet, but not LC with CR diet, would improve macro- and microvascular endothelial function in women with obesity. Twenty-one healthy women with obesity (age: 33 ± 2 years, body mass index: 33.0 ± 0.6 kg/m2; mean ± SEM) were randomly assigned to receive either a LC diet (~10% carbohydrate calories) with CR (n = 12; 500 calorie/day deficit) or a LC diet without CR (n = 9) and completed the 6-week diet intervention. After the intervention, macrovascular endothelial function, measured as brachial artery flow-mediated dilation did not change (7.3 ± 0.9% to 8.0 ± 1.1%, p = 0.7). On the other hand, following the LC diet intervention, regardless of CR, blocking nitric oxide production decreased microvascular endothelial function, measured by arteriolar flow-induced dilation (p ≤ 0.02 for both diets) and the magnitude was more than baseline (p ≤ 0.04). These data suggest improved NO contributions following the intervention. In conclusion, a 6-week LC diet, regardless of CR, may improve microvascular, but not macrovascular endothelial function, via increasing bioavailability of nitric oxide in women with obesity.