“Carbs are twigs that burn fast, fats are logs that burn slow. Eat them together and your body burns the twigs first while storing the logs as fat.”
Stop Sabotaging Your Fat Loss: The Hidden Truth About Carbs + Fat Combinations!
Since diving deep into body recomposition nutrition, I've discovered one of the biggest mistakes that keeps people stuck in fat storage mode:
Eating high carbs (especially refined, simple carbs) and high fat together.
Let's dive deeper into it!
Why Consuming Carbs + Fat Together Can Increase Fat Gain
Your body is designed to use one primary fuel source at a time: either carbohydrates or fats.
When you consume both in significant amounts in a single meal, you create what experts call “metabolic gridlock” or “fuel competition”.
What happens biologically:
- Carbs trigger a spike in insulin, a hormone that shuttles glucose into cells and inhibits fat burning.
- Fat usage gets sidelined. Insulin simultaneously increases the activity of lipoprotein lipase, making circulating fat easier to store in adipose tissue.
- You’ve essentially given your body too much energy, so it burns the carbs and stores the fat.
Studies show that glucose oxidation suppresses fat oxidation and vice versa. Research published in Cell Metabolism (2019) demonstrates that fructose consumption "decreases dietary fat oxidation" through "impaired expression of fatty acid oxidation genes and by modifying the mitochondrial proteome."
Additionally, another study by Wolfe (1998) shows that "increased glucose oxidation limits oxidation of long-chain fatty acids directly by inhibiting their transport into the mitochondria."
Why This Combination Is So Addictive
Eating carbs and fats together stimulates multiple reward centers in the brain — far more than either one alone.
This “double dopamine hit” leads to overconsumption and cravings.
In other words, this combination activates a more intense dopamine response than either macronutrient consumed on its own.
That's why you can't stop at one slice of pizza or one cookie.
This double reward response makes it easier to overeat, creating a vicious cycle of cravings and fat storage.
The Smarter Way: Pick ONE Main Fuel Source
To avoid confusion at the cellular level, separate your energy sources:
🥗 Diet A: Carbs + Low Fat (Low Glycemic + Low Fat Diet)
- Lean protein + complex carbs
- Low fat (under 30g per day)
- Examples: Chicken breast with brown rice, egg whites with oats
🥑 Diet B: Low/No Carb + High Fat (essentially Keto Diet)
- Protein + healthy fats
- Carbs under 30–50g daily
- Examples: Eggs with avocado, salmon and olive oil
🧠 Diet C: Low/No Carb + Low Fat (Low Fat “Fat-Burning” Diet)
- Lean Protein is the priority
- Minimal fat and carbs
- Examples: Chicken breast with veggies, egg whites with leafy greens
In all cases: Choose Low Glycemic Foods, especially the carbs!
In all cases: Prioritize protein!
It has the highest thermic effect, preserves muscle, and produces minimal insulin response.
Common High-Fat + High-Carb Traps to Avoid
- Donuts (sugar + frying oil)
- Ice cream (sugar + cream fat)
- Pizza (white flour + cheese)
- Burgers with buns (refined bread + fatty meat)
- Bagels with cream cheese (white flour + high fat)
The Cheeseburger Example
Dr. Becky is a college instructor of nutrition science from drbeckyfitness.com who explains how different macronutrients affect metabolism and fat storage in this video.
According to her cheeseburger example, when you eat refined carbs and fats together, the refined carbs (bun) quickly spike insulin and supplies your cells with easy energy, while the slower-digested fats arrive when your energy needs are already met.
Since insulin is present from the carbs and the cells are already “satisfied” firsthand from the easy energy, it shuttles those fatty acids directly into fat storage rather than using them directly for energy.
The best recommendation is to eat the meat and cheese but throw away the bun, or better yet, choose a salad with healthy fats instead of a sandwich to avoid this fat-storing combination!
My Personal Experience with Fuel Separation
I switched from low glycemic carb + low-fat (Diet A) to low-carb/low-fat (Diet C) for a month-long fat loss challenge before Easter 2025.
The simplicity was game-changing: no need for rice prep, no pasta boiling, just protein and greens.
The outcome included exceptional fat loss, sustained energy, and effortless meal prep!
Is it sustainable?
Absolutely.
While I default to including complex carbs for variety sake, I cycle back to the low-carb approach when I want accelerated results.
The key:
Commit to one approach for a full month.
Don't bounce between fuel types weekly or daily—this confuses your metabolism about whether to burn incoming carbs or stored body fat.
Pick your fuel strategy and stick with it for at least 30 days before switching.
What If You Want to Combine Carbs and Fats?
You can, but just keep these guidelines in mind:
- Keep portions small to avoid overeating
- Favor unrefined, complex carbs (e.g., vegetables, brown rice, whole wheat bread/pasta)
- Eat plenty of fiber first/alongside the meal to slow glucose absorption and reduce the insulin spike
Typically this is mostly for maintaining current weight/body composition rather than striving towards specific goals like getting lean/bulking goals.
Final Takeaway: Choose Fuel Clarity Over Confusion
When insulin is present and elevated (typically from any type of carbohydrate consumption), the body prioritizes burning glucose and will tend to store the dietary fat rather than burn any for energy.
There’s a metabolic "traffic jam" from consuming both high carbs + high fat which essentially leads to greater tendency for fat storage, because insulin essentially tells the body to use the readily available glucose first while encouraging fat storage since it already fulfilled energy requirements from the carbs.
All in all, the truth isn’t that you can’t ever mix carbs and fats, but that you shouldn’t do it frequently or in large volumes, especially if your goal is fat loss and body recomposition, not just maintenance.
Additional Resources
Should You Prioritize Fat or Carbs After Reaching Protein Target?
Find out the strategic approach for choosing between carbs and fats based on whether you're trying to bulk up or lean out here at this video extract from The Mind Pump Show, a fitness and health-focused show known for its unfiltered, science-backed advice on training, nutrition, and overall wellness and hosted by four personal trainers: Adam Schafer, Sal Di Stefano, Justin Andrews, and Doug Egge.
What Really Happens In Metabolic Gridlock?
In this video, Thomas DeLauer, distinguished Health & Fitness Expert and Business Performance Coach known for his expertise in nutrition, intermittent fasting, and high-performance training, explains more about the phenomenon called "metabolic gridlock" that occurs when you combine large amounts of fats and carbs, comparing it to a traffic jam in your cellular machinery.
Learn why your mitochondria can only process one fuel type at a time, the brain science behind why certain food combinations trigger addictive responses, and the fiber-loading strategy for damage control during cheat meals.
A Simple Step to Try Today:
For each meal, choose:
- Carbs + low fat, OR
- Fats + low carb
Meanwhile, always keep protein the priority and constant and choose mainly low-glycemic options!
Track how you feel and how your clothes fit after two weeks.
Reply and let me know your results!
PS...For recipe ideas following a low glycemic + low fat approach (Diet A), check out my Instagram, where I share photos of homemade ovo-lacto vegetarian recipes!
PPS...Tired of confusing nutrition advice from the "cycle-syncing" hype?
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References:
- Softic, S. et al. (2019). Cell Metabolism - https://www.cell.com/cell-metabolism/fulltext/S1550-4131(19)30504-2
- Wolfe, R.R. (1998). Metabolic interactions between glucose and fatty acids in humans. American Journal of Clinical Nutrition - https://academic.oup.com/ajcn/article/67/3/519S/4666039