by 
Main Takeaways
- Some racial and ethnic groups, including Black individuals, tend to produce more insulin in response to high-carb meals. This may increase the risk of obesity and diseases related to insulin resistance.
- A new clinical study suggests that Black women who are high insulin producers benefit significantly from a low-carbohydrate diet.
- For people at high risk of insulin-related obesity, reducing carbs—rather than just calories—may be key to reducing health disparities.
Understanding the Disparity
In the U.S., Black women experience obesity at significantly higher rates than White women (57% vs. 40%). This disproportionate prevalence contributes to serious health burdens—diabetes, cardiovascular disease, and cancer, among others.
While many studies have explored behavioral factors like diet and exercise adherence, the outcomes of standard obesity treatments for Black women have often been disappointing. A 1991 review of two major hypertension trials found that Black women lost about 6 pounds less than White women over 18–36 months. More recent research attributes this to factors such as lower diet quality and physical activity levels, possibly related to stress or cultural influences.
This might lead to the conclusion that unchangeable factors—like genetics or entrenched environmental conditions—are responsible. However, there’s an alternative explanation that offers hope: a biological factor that can be modified—namely, insulin response to carbohydrate intake.
The Role of Insulin in Obesity Risk
Insulin is a hormone that regulates how our bodies process and store energy. When you eat a meal rich in carbohydrates, your blood sugar rises, prompting your pancreas to release insulin. In some individuals—especially among Black populations—this response is amplified, leading to higher levels of insulin and insulin resistance, even after adjusting for body weight and fat distribution.
This difference has been observed not only in adults [6], but also in children [7]. These insights led researchers to ask: Can a low-carb diet help mitigate this risk by reducing insulin production?
New Evidence: A Clinical Trial in Black Women
A study recently published in the journal Obesity directly addressed this question. Martins and colleagues [8] conducted a randomized trial involving 69 Black women with obesity, assigning them to either:
- A low-fat diet (55% carbs, 20% fat), or
- A low-carb diet (20% carbs, 55% fat).
For 10 weeks, participants were provided with 60% of their daily energy needs (to induce weight loss), followed by a 4-week maintenance phase at 100% of their energy requirements.
Key Results:
- Participants lost an average of 12 pounds overall.
- Among women with lower insulin sensitivity, those on the low-carb diet lost significantly more fat (11 lbs vs. 4.5 lbs on the low-fat diet).
- The low-carb diet also preserved total energy expenditure, whereas energy expenditure dropped significantly on the low-fat diet.
These findings support similar results from a large feeding study published in the BMJ [9], reinforcing the idea that the composition of the diet—not just the number of calories—can affect metabolism and fat loss.
Rethinking the Calories In/Calories Out Model
These results challenge the conventional “calories in, calories out” model of weight loss. The study implies that two diets with the same calorie count could have very different effects—one leading to fat gain, the other to fat loss—depending on how they influence insulin and metabolism.
Although the study had a relatively small sample size and short duration, the findings are consistent with other research on personalized nutrition and metabolic differences across individuals [10, 11].
The Carbohydrate-Insulin Model (CIM) Explained
The Carbohydrate-Insulin Model (CIM) offers a compelling explanation for these effects. According to CIM [12]:
- High-carb meals cause a rapid spike in blood glucose.
- This triggers a surge in insulin, increasing the insulin-to-glucagon ratio.
- The body shifts to store energy as fat, rather than burning it.
- As a result, fewer calories are available to fuel the brain and muscles, leading to:
- Increased hunger
- Lower energy levels
- A slower metabolism
In this model, overeating is not the root cause of obesity—it’s a symptom of disrupted metabolism caused by excessive insulin production.
For people predisposed to high insulin secretion—whether due to genetics or early-life adversity—a high-carb diet may drive a cycle of fat gain, cravings, and metabolic slowdown. This makes standard advice to “eat less and move more” ineffective for long-term weight loss in these individuals.
Implications for Public Health and Equity
The study by Martins et al. suggests that Black women with insulin resistance may benefit especially from low-carbohydrate diets—not just for weight loss, but also for improving broader metabolic health.
This approach could help reduce health disparities and minimize stigma, by framing obesity not as a personal failure of willpower, but as a consequence of individual biology interacting with dietary environments.
With obesity-related diseases on the rise, especially among high-risk groups, well-funded, long-term studies on the benefits of low-carb diets in racially diverse populations should be a public health priority.
Conclusion
This emerging body of evidence points to a critical insight: Different bodies respond differently to the same diet. For Black women with high insulin levels, a low-carbohydrate diet may offer a targeted, effective, and empowering approach to weight management.
Personalized, biologically informed nutrition strategies are not only more effective—they may also help bridge the gap in health outcomes across racial and ethnic lines.
