Seven days of high-calorie high-fat diet leads to a blunting of meal-induced adipose tissue microvascular blood flow responses in healthy individuals without any changes in adiposity or differences in fasting or postprandial circulating concentrations of gut hormone gastric inhibitory polypeptide.
Key Findings
Results
Acute overfeeding via a 7-day high-calorie high-fat diet blunted meal-induced adipose tissue microvascular blood flow in healthy adults.
Study involved n=14 healthy adults undergoing a 7-day high-calorie high-fat (HCHF) diet intervention.
Experimental procedures were performed on days 0 (pre-), 4 (mid-), and 8 (post-intervention).
Adipose tissue MBF increased above baseline at 60 min following the mixed meal challenge at pre-intervention (P = 0.002) and mid-intervention (P = 0.007), but not at post-intervention (P = 0.231).
The blunted MBF response occurred despite no changes in body composition or adiposity.
Results
Seven days of HCHF diet did not change body composition measures including total, trunk, gynoid, android, or visceral fat.
Body composition was assessed at pre-, mid-, and post-intervention time points.
Total fat, trunk fat, gynoid fat, android fat, and visceral fat were all unchanged after the 7-day intervention.
This confirms that the observed vascular impairments were independent of changes in adiposity.
The absence of adiposity changes distinguishes this acute overfeeding model from chronic obesity.
Results
Plasma gastric inhibitory polypeptide (GIP) concentrations increased significantly following the mixed meal challenge but did not differ between pre- and post-intervention.
Plasma GIP concentrations significantly increased at all time points from 0 to 120 min following the mixed meal challenge (all P < 0.001).
There were no differences in fasting or postprandial GIP concentrations between pre- and post-intervention.
GIP had been proposed as a mechanism linking meal ingestion to adipose tissue microvascular blood flow.
The unchanged GIP response suggests GIP is not responsible for the blunted adipose tissue MBF observed after the HCHF diet.
Results
Adipose tissue microvascular blood flow increases in response to a meal in healthy adults at baseline, consistent with prior literature.
Truncal subcutaneous adipose tissue MBF was measured in response to a mixed meal challenge.
MBF increased above baseline at 60 min following the MMC at pre-intervention (P = 0.002).
MBF also increased at mid-intervention (P = 0.007), indicating the response was still partially intact after 4 days of HCHF diet.
This postprandial MBF response was completely abolished by post-intervention (P = 0.231).
Discussion
Acute overfeeding-induced impairment of adipose tissue microvascular blood flow likely operates through mechanisms other than GIP or changes in adiposity.
The blunted MBF response occurred without changes in GIP concentrations, ruling out GIP as the primary mediator.
The blunted MBF response occurred without changes in adiposity, ruling out fat accumulation as the primary mediator.
Prior work by this group showed acute overfeeding causes hyperinsulinemia and impairs meal-induced skeletal muscle MBF in healthy people.
Authors conclude that 'future studies should investigate other potential mechanisms behind the HCHF diet-induced vascular impairments to prevent chronic disease risk.'
Background
This study represents the first investigation of adipose tissue microvascular blood flow responses in healthy individuals after a short-term high-calorie high-fat diet intervention.
Prior research had established that adipose tissue MBF is blunted in people with insulin resistance, obesity, and type 2 diabetes.
The current study extends this work by demonstrating that the blunting can occur acutely, within 7 days, in metabolically healthy individuals.
The study used a mixed meal challenge to assess postprandial vascular responses at three time points.
Described as 'New & Noteworthy' by the authors as the first such study in a healthy population with this dietary intervention.
What This Means
This research suggests that eating a high-calorie, high-fat diet for just one week can impair the body's normal blood flow response in fat tissue after a meal, even before any weight gain or increase in body fat occurs. In healthy adults, eating a meal typically triggers increased blood flow to fat tissue, which helps the body process and store nutrients properly. After seven days of overfeeding, this normal response was completely abolished, even though participants showed no measurable changes in total body fat, belly fat, or any other fat deposits.
Interestingly, this study also tested whether a gut hormone called GIP (gastric inhibitory polypeptide), which rises after eating and had been thought to drive this blood flow response, was responsible for the impairment. GIP levels rose normally after meals and were unchanged by the diet intervention, suggesting GIP is not the reason blood flow was blunted. This means other mechanisms — not yet identified — are likely responsible for how overfeeding harms blood vessel function in fat tissue.
This research matters because impaired blood flow in fat tissue has been linked to insulin resistance and higher risk of chronic diseases like type 2 diabetes. The finding that these vascular problems can emerge within just one week of overeating, before any visible fat gain, suggests that early dietary changes may trigger harmful processes in the body sooner than previously appreciated. Future research will need to identify what those other mechanisms are in order to find ways to prevent diet-related vascular damage.
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Brayner B, Mason S, Karimi E, Keske M, Roberts-Thomson K, Parker L, et al.. (2026). Acute overfeeding impairs meal-stimulated adipose tissue microvascular blood flow in healthy adults independent of changes in adiposity.. American journal of physiology. Endocrinology and metabolism. https://doi.org/10.1152/ajpendo.00028.2026