Add Fat To Lower Insulin Response? Nope

Health, Nutrition, Weight Loss Add comments

It’s time to clear something up.

Books, magazines, and weight loss courses have all been spreading a bit of misinformation about eating fats and your body’s insulin response.

After vilifying  insulin response to foods, “experts” are recommending adding healthy fats to carbohydrates to reduce insulin in your blood after meals.  Here are just 3 examples I’ve seen today:

  • Adding peanut butter to your whole grain english muffin
  • Adding butter to your baked potato
  • Adding sesame oil to your steamed rice

english muffin with peanut butter

The idea is that the fats will slow/level out the rise in blood sugar in prevent a big insulin release after eating.


Fat doesn’t cause an immediate insulin response, it’s true.  But when added to a protein or carbohydrate, fat either has no effect on insulin response or else it slightly increases insulin response.

Sorry, but it doesn’t slow insulin down.

But there’s good news!  When fat REPLACES an equal caloric amount of carbohydrates, the insulin response is reduced.

To really make it clear, let’s use one of the examples above.  If you add butter to your baked potato, your insulin response will be the same or a little greater than if you ate the baked potato alone.  But if you eat half a potato with butter (even if you replace, calorie for calorie the butter for half a potato) your insulin response will be much lower than if you ate the whole potato plain.

baked potato guinea pig

So the key to using fats to lower insulin response isn’t in adding them to the meal, as if they were an anchor being dragged to slow your food.  The key is to exchange carbohydrates for fat to produce lower insulin levels.

Most of the confusion comes from people’s failure to recognize the difference between adding fat versus substituting fat.

See, adding fat to a meal does (in fact) slow down the rise in blood sugar that follows eating carbohydrates.  Since your insulin response is usually – in healthy people – aligned with the rise in blood sugar, it makes total sense to assume that adding fat to a meal would reduce the insulin response to that meal.

It makes sense, but that isn’t what actually happens!

As I said before, it turns out that insulin is either not affected or it rises with the addition of fat to carbohydrates.

(This is probably related to gastric inhibitory polypeptide, which is a hormone secreted from the pancreas in response to eating fat and which can heighten insulin reaction)

What about the insulin effects of protein?  Everything so far has focused on carbohydrates.  Well, first off, protein doesn’t raise insulin levels as much as carbohydrate… not by a long shot.

But it does affect insulin levels a little (about 30% as much as carbohydrate).  There are three main factors that determine your insulin response to protein:

1.  Fat Content.  The more fat versus protein, the lower your insulin response.

2. Amino Acid Profile.  Sources that are higher in lysine (example: beef) bring on more insulin than other protein sources

3. Processing.  The more processed your protein is, the more it will raise your insulin.  Ground beef doesn’t require as much digestion as steak, so it enters your bloodstream more rapidly.  (Ground meat actually ends up giving you more calories as well, because you don’t use up as much energy during the digestion process.  For a fascinating look at how cooking and grinding food shaped human evolution, I recommend reading Catching Fire: How Cooking Made Us Human)

t bone steak

Fortunately, protein stimulates glucagon release as well, so you don’t need to worry as much about the insulinogenic properties of protein as you do about carbohydrates.  (If you don’t know much about glucagon, think of it as the opposite of insulin).

What does all this mean from a practical standpoint?  How then can you control the insulin response to bread, protatoes, rice – to go with the examples from earlier in this post?

In fact, why worry about the insulin response to carbohydrates at all?

Well, to control the insulin response from carbs… stop eating so many carbs!  Use the insulin response with strategically timed meals, after a workout or as part of a carb cyling plan, for example.

turtle eating strawberry

And you should be concerned about bumping insulin when you’re eating fat because when fat is consumed while your body is in fat-storage mode (high insulin), it is more likely to end up as bodyfat.

When your insulin levels are high, everything you eat is more liable to end up in your fat stores.  Fat especially heads straight for your fat cells when your insulin is high, especially because insulin causes fat burning to stop.

Translation: Fat is fattening IF you are in a fat storing mode (high insulin).

Your solution is to not eat fat when your insulin levels are high, and keeping carbs low the rest of the time.  You want to keep fat and insulin producing carbs apart from each other.

One situation would be to have protein and fat at every meal except for one or two meals right after your workout.  Here’s a sample schedule:

7 am: Protein + Fat

11 am: Protein + Fat

2 pm: Protein + Fat

4 pm: Workout

5 pm: Protein + Carbs

7 pm: Protein + Carbs

Or if you workout in the morning:

6 am: Workout

7 am: Protein + Carbs

10 am: Protein + Carbs

1 pm: Protein + Fat

4 pm: Protein + Fat

7 pm: Protein + Fat

Another option is to have higher carb “refeeds” every few days.  This is a good strategy when you’re looking to gain muscle and lose fat.

Day One: Several moderate protein, moderate fat meals

Day Two: Same as Day One

Day Three: Moderate protein, low fat meals during the day, 3 hour high carb, low protein, minimal fat refeed after your workout

Day Four: Same as Day One

Day Five: Same as Day One

Day Six: Same as Day One

Day Seven: Moderate protein, low fat meals during the day, 3 hour high carb, low protein, minimal fat refeed after your workout

food log body

What a plan like this does is keep you in fat burning mode most of the time, but still bump insulin to keep you anabolic and allow you to build muscle.  If you have more fat to lose, you’d want to go longer between refeeds.  If you’re already lean and looking to build muscle, you can have your refeeds closer together.

So to loop back to the original point of this post, adding fat to carbs doesn’t benefit you from a hormonal standpoint, in fact, it makes it more likely you’re going to store that meal as fat.

EDIT: I was asked why, if adding fat to meals doesn’t help with insulin, does adding fat make you feel fuller longer?

The answer is simple: You ate more calories!

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