How a Low-Fat Diet Can Keep You Full: The Hidden Science

Imagine a diet that keeps you full and satisfied without cutting carbs.  

Sounds impossible?  

Think again!  

While satiety has exploded recently in the low-carb scene, the untold story of satiety on a low-fat diet might surprise you.  

Dive in to uncover how millions around the world achieve optimal hunger control and nutrition with fewer fats and more carbs.  

Ready to decode the secrets of the low-fat satiety phenomenon?  

Let’s get started!

It’s Just Not the Carbs that Make You Fat

Many people wonder if satiety is really a thing on a low-fat diet.  But the reality is that most of the world’s population lives on a lower-fat diet, especially in lower and middle-income countries.   

In this article, we’ll look at the key factors that align with greater satiety on a lower fat, higher-carbohydrate diet.  We’ll also highlight the danger zone that aligns with overeating on a lower-fat diet and how to achieve greater satiety to minimise hunger with less energy.  

This chart shows the satiety response to protein, fat and carbs for 303,637 days of data for people on a lower-fat diet (i.e. less than 31% fat, or the median fat intake in our dataset). 

Let’s break down what it means and how someone on a lower-fat diet could optimise their macros and food choices for greater satiety.

Low Fat, Low Satiety Danger Zone

The low-fat, low-satiety danger zone is where we simultaneously hit the carbohydrate bliss point (60% carbs) and protein bliss point (12.5% protein), with the remainder of the energy coming from fat. 

The snip from our interactive food search tool below shows that the foods that fit into this hyperpalatable window include bread, mashed potatoes (with butter) and milkshakes, which are easy to overeat. 

Satiety Scenario 1: Higher Carb, Low Protein

Towards the far right of the chart, we see that a very high-carb diet (i.e. greater than 70% carbs) tends to be harder to overeat.  This typically also coincides with a very low-protein diet. 

While we often talk about protein leverage and the power of a higher protein %, people on a very low protein diet (less than 12.5% protein) also tend to eat less. 

The snip from our food search tool shows that high-carb, low-protein foods are typically fruit, plain rice, and plain potato.   

If you look hard, you might also spot a few breakfast cereals.   The reality is that you would probably struggle to binge on dry breakfast cereals.  However, once you add some milk (per the serving suggestion), you’ll get a more palatable blend of fat and carbs.  

However, it’s worth noting that while a very high carbohydrate diet is hard to overeat, very few people maintain it.  Most people gravitate back toward the carb+fat combo. 

A very high-carbohydrate diet can also make it more challenging to obtain adequate protein and several other nutrients, like vitamin B12 and omega-3.

Satiety Scenario 2:  Higher Protein, Moderate Carb

But what if we opt for a higher-protein, low-fat, moderate-carb approach that also involves eating less? 

The snip below shows foods with less than 50% carbs and greater than 25% protein.  The foods that fit these macro parameters are primarily seafood, lean meat and non-starchy vegetables.   With adequate protein, these lower-fat foods will still provide plenty of nutrients and be hard to overeat. 

Interestingly, once we get plenty of protein, there isn’t much difference between a low-carb and a low-fat diet.  When we focus on getting adequate protein, minerals and vitamins, so long as your blood sugars are in the healthy range (i.e. a rise of less than 30 mg/dL or 1.6 mmol/L after meals), it doesn’t matter too much if you prefer to get more of your energy from fat or carbs.

But What About Insulin? 

When discussing lower-fat diets, people from a low-carb background often ask, ‘But what about insulin?  Won’t all that carbohydrate make me fat?’

Moving to a low-fat or lower-carb diet for people injecting insulin, compared to the modern processed diet of fat+carbs with minimal protein, will help.  So long as your blood glucose levels are in the normal healthy range, you can tailor your fuel source to suit your preferences and activity levels. 

For people with diabetes who are taking exogenous insulin, a low-carbohydrate approach tends to have more stable glucose and smaller bolus insulin doses (which are easier to manage and correct) but higher basal doses to cover the long-term effects of dietary fat. 

Meanwhile, low-fat diets (e.g., as advocated by Mastering Diabetes) require less basal insulin but higher bolus doses, likely poorer glucose control, and a higher total daily insulin demand. 

I strongly prefer Dr Bernstein’s Law of Small Numbers approach, which provides much better glucose stability and potentially higher nutrient density.

For more details, see:

• Decipher the Insulin Code: The Truth About Your Insulin Resistance
• The Nutrient Showdown: Why Low-Carb and Low-Fat Diets Both Work and
• Mastering Type-1 Diabetes Management: A Comprehensive Guide to Thriving with T1D

Summary

• Satiety on a lower-fat diet is possible.  
• The key is avoiding the “low-fat, low-satiety danger zone” (60% carbs and 12.5% protein)—think bread and milkshakes.
• A high-carb diet (> 70% carbs) can be satiating, but it potentially lacks protein and some nutrients, such as omega-3 and B12. 
• If you prefer lower fat, focus on lean protein and moderate-carb options like lean meat, seafood, and veggies.

More

• Avoid These 2 Diet Danger Zones for Increased Low-Carb Satiety
• Low Carb vs Low Fat Diets for Weight Loss and Nutrient Density
• Oxidative Priority: Unlock Your Fat-Burning Potential
• The Nutrient Showdown: Why Low-Carb and Low-Fat Diets Both Work
• Macros Masterclass