Home Low Carbohydrate diets How eating more protein and less carbs can cut your calorie intake...

How eating more protein and less carbs can cut your calorie intake by half


In my paleo nutrition seminar I use this study to illustrate how food affects hormones that in turn affect appetite.

(Note: Next seminar Auckland 4th December, Papamoa 1st December – more info here: Paleo Nutrition Seminars New Zealand)

In order to lose weight – you must eat less fuel. Fuel not used will get stored in your fat cells. There are two main ways to eat less (disregarding drugs and surgery):

  • Have lots of willpower
  • Eat a diet that you feel more sated on and naturally eat less food

Willpower does not usually last long, so the obvious choice is a diet whereby you eat less without feeling hungry.

This study illustrates clearly how and why eating more protein and less carbohydrates at each meal can literally halve the amount of food you want to eat.

But first, lets have a quick look at different macronutrients and their roles in your body:

Carbohydrates comprised of sugars and starches, and are built from mainly glucose and fructose molecules, sugars are 1- 2 molecules long and starches are many molecules long.

During digestion the links between the molecules are snipped apart by intestinal enzymes into single molecules. After crossing the gut barrier they go into the blood stream (your blood gets sweeter). Fructose gets taken up by the liver for processing, glucose on the other hand can readily be used by the cells for fuel.

carbohydrates  (2)

Your pancreas senses the ‘sweetness’ of your blood and sends insulin out in order to get the sugar transferred out of the blood into cells where it can be ‘burnt’ for fuel. As a general rule, the more sugar in your blood – the more insulin you need to send out to remove it.

Protein on the other hand is made of strings of amino acids. During digestion peptidases (specific enzymes that snip apart an amino acid from its neighbour) break down these long strings.


The single amino acids then cross the gut barrier and are transported around the body to be used to make up proteins our body needs, like enzymes, muscle, bones, skin etc.

Protein like carbohydrate also triggers the release of insulin (something many people don’t realise) An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Here are some high protein foods compared to white bread, showing insulin response:

insulin response to food1insulin response to food

However protein triggers the release of other hormones; in particular glucagon which increases satiety, and the release of glucose from the liver (Glucagon, Dietary Protein, and Low-Carbohydrate Diets)

How a higher protein, lower carb meal decreases your appetite compared to a high carb meal:

So lets have a look at this study which compares two different high carbohydrate meals (high and moderate glycemic index) with a lower carbohydrate meal (more protein and fat, less carbohydrates) and the effect of each on hormones, hunger and consequent food consumption.

The study (High Glycemic Index Foods, Overeating, and Obesity):

  • 12 obese teenage boys, crossover study, 3 separate 24 hour admissions to hospital, 1 -2 weeks washout periods in between
  • 3 different meals were evaluated, high GI, moderate GI and low GI, one on each admission. (Note: all meals had identical calories)
  • The boys ate the same meal for breakfast and lunch and were allowed to eat as much or little as they liked for the rest of the day. The exact amount consumed was measured.
  • A number of measurements were taken – blood sugar, insulin, glucagon, epinephrine, hunger ratings.

Here are the actual meals, two meals are typical high carbohydrate / grain /dairy – the type of meal that would be considered a healthy breakfast by just about all mainstream dietitians  – each has a different glycemic index, one is slow cooking oats, the other instant oats. The other meal contains less (and non grain) carbohydrates, and more protein and fat – in a Zone diet macronutrient ratio.


Low GI

Medium GI

High GI

Foods 55 g Whole egg 63.9 g Steel-cut oats * 60.9 g Instant oatmeal *
45 g Egg white 160 g 2% Milk 160 g 2% Milk**
40 g Low-fat cheese 15 g Half  & Half cream 15 g Half  & Half cream
200 g Spinach 16.0 g Fructose 19.0 g Dextrose
30 g Tomato 0.0 g Saccharine 0.2 g Saccharine
185 g Grapefruit 397 g Water 397 g Water
115 g Apple slices
% Energy from carbohydrate 40 64 64
% Energy from protein 30 16 16
% Energy from fat 30 20 20
Energy density (kJ/g) 2.46 2.52 2.52



The first graphs show the elevation of blood glucose after the different meals; as you would expect, the two higher carb meals (circle, square) had a much higher glucose elevation than the moderate carb meal. Insulin response mirrors the carbohydrate content of the meals.

Compare the two high carb meals: The quick cook oats had the greatest increase in blood sugar, and around the 3.5 hour mark – it continues to drop – below the fasting level. The range shows all boys responded this way. When your blood sugar goes low, your body responds by elevating the stress hormone epinephrine or adrenaline. This is shown clearly on the lower graph. There is a large increase in epinephrine in the high GI meal compared to the other meals. Adrenaline is the flight / fight hormone, and is released to increase blood glucose via glycogenolysis. The moderate GI meal surprisingly had almost no adrenaline response, and the high protein, low carb meal very minimal. (Does this mean that carbohydrates – if they are very slow release are beneficial? Or did the epineprine rise as glucagon levels fall around the 4 hour mark?)

reponses-to-low-med-high-gi-meals (2)Hormonal and metabolic changes after test breakfasts. Plot symbols: square, high-GI meal; circle, medium-GI meal; triangle, low-GI meal.

reponses-to-low-med-high-gi-meals epinephrine (2)


Glucagon is released by the pancreas in response to protein, it has an appetite suppressant effect, as well it elevates the amount of glucose in the blood by promoting gluconeogenesis and glycogenolysis.

In the graph below you’ll note that glucagon is suppressed by the high carbohydrate meals and increased in the higher protein meal for around 4 hours post meal.

glucagon response

So the effects of these foods on hormones is interesting – but what about subsequent hunger, and food consumption?

The boys had the same meal for breakfast and lunch, then for the rest of day they could eat as much as they wanted from the food provided. They also gave a hunger rating every hour for the 5 hours following breakfast.

This graph shows the difference in hunger following each meal – the hunger experienced was significantly greater on the high carb meals:

Change in hunger after test breakfasts. Hunger is determined by a 10-cm analog scale.

Food consumption for the rest of the day

When the boys were allowed to consume what ever they wanted following lunch, the first thing to note is that some boys got hungry and started to eat within 1 hour of consuming the quick cook oats. The boys who ate the higher protein lower carb meal did not start to eat until the 3 hour mark. By the end of the day the difference is dramatic – those who ate the high refined carb (quick cook oats) meals ate nearly double the amount of food compared to those that ate the higher protein lower carb meal.


Cumulative food intake after test lunches. Food intake is quantitated as total energy consumed, expressed in megajoules, and normalized to a predicted RMR of 8.4 mJ (2000 kcal).

And in another study just released – having a high protein breakfast, compared with a high carb, or no breakfast, helped women eat less during the rest of the day:

Protein-Rich Breakfast Helps Curb Appetite Throughout the Morning

Take home points:

If you want to control your hunger – eat protein at every meal, start your day with protein at breakfast – you will elevate the hormone glucagon which increases satiety. (We eat meals the wrong way round – try eating dinner for breakfast) And no yoghurt is not that high in protein – try protein dense food like eggs or meat, use this chart and get a minimum of 20 grams, ideally 30. Protein amount in eggs, seafood, meat and dairy.

Eat whole vegetable and fruit carbohydrates rather than grains (this article describes further benefits of vegetable starches over grain starch: Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity)

Add a little fat to your meal, it slows down the digestion of carbohydrates and also helps satiety.

Think of every meal as controlling blood glucose and satiety hormones for the following 4 – 6 hours, and experiment with your meals to find ones that manage your hunger best.

For some it means more fat and less carbohydrates – particularly if you are insulin resistant. In this case stick to non starch carbohydrates and add more healthy fat like avocado to your meal along with the protein. Watch this excellent video from NZ scientist Dr Grant Schofield on this topic here:

Low carb, high fat, challenging beliefs





  1. Julianne, a fabulous post w/ great info, as always. I love the detail, & have always liked graphs since they are so visual. There is one graph that is throwing me off, though. If I’m reading the plasma epinephrine graph correctly, it shows the epinephrine level on the low g.i. meal (triangles) fell in the Middle range around the 4 & 5 hour mark. But, the statement says that the only meal with no adrenaline response was the high protein, low carb meal (which makes sense to me). Could the circles & triangles on this one graph have been inadvertently reversed? I have an older son with depression who often won’t eat unless I prepare the food for him. At those times, I can be sure he eats high protein. But, there are times he will gulp down a large sugary drink or high carb meal that he goes out & gets himself. I want to show him this great info & focus on the adrenaline, fight / flight response that is evoked w/ high carb, but he is likely to notice the apparent discrepancy I saw. Please clarify. Thanks So much!

    • Thanks – I obviously saw what I wanted to see! I’ve changed the text. I notice there was a dip in slight dip in blood sugar in the higher protein group around the 4 hour mark, as well as a decrease in glucagon – maybe this is why the epinephrine went up a little, to increase gluconeogenesis. Not much though compared to the high glycemic meal. Interesting though.
      I like visuals too – always helps explain things so much better than just words.

  2. Hi Julianne,
    I just want to start by saying that I love your blog and some of your posts really helped me.
    I don’t have diabetes but I’ve been suffering from hypoglycemia since last year. I even passed out several times with levels like 35 and was unable to eat carbs without crashing to levels like 35, 45 min later. I also did some tests at the hospital (they don’t think reactive hypoglycemia is a real thing and only believe in diagnosis like an insulinoma – doctors here are extremely misformed). However they found out I have nocturnal hypoglycemia in the 40’s during the whole night and that I spend half of my day hypoglycemic.
    I started investigating for myself and I thought I had LADA or something like that but apparently after following the paleo diet my symptoms improved alot. In the first months the hypoglycemia started to happen at the 2h peak instead of the 45min-1h. Now I barely have it (at least during the day – I plan to see what happens at night in my next visit to the hospital – since 40 all night is very dangerous)
    I’ve been checking during the night for a week and surprisingly I didn’t see low numbers, not even close to 40. My glucometer shows numbers around 100 every single night at 2 am. I mean every single night. I started to suspect again this has something to do with diabetes after all but When I wake up around 8.am it’s always 70 or in the very low 70’s. I have to point out I eat some sort of Perfect Health Diet now (not paleo per se). Do you have any idea why I have those kind of numbers now? there seems to be a dysregulation but I don’t think if that’s relevant or not and would like to have your opinion. Also, another question that really confuses me is that I’ve been eating a high protein breakfast with fat and a little bit of carbs for a couple of weeks now (not 50g of protein but fairly high protein for what I was used – usually a couple of eggs and a piece of meat or tuna) and after 1h my blood sugar is usually 110, sometimes goes up to 120. Why does this happen? should I stop eating like this? If you could help me with your opinion I would be very grateful.
    Thank you very much and sorry for my english – I’m from portugal.

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