Clinically reviewed by Associate Professor Christopher O’Donnell, Nurse Practitioner, FACN · Founder and Clinical Director · AHPRA NMW0001453715 · Last reviewed
Protein is the most satiating of the three macronutrients, reducing appetite through effects on gut hormones and a higher thermic effect of digestion. During weight loss, adequate protein also preserves muscle mass, which maintains energy expenditure and supports long term maintenance.
Why protein affects appetite more than other nutrients
Protein influences appetite through several mechanisms at once. It stimulates release of satiety hormones from the gut, including peptide YY and cholecystokinin, which signal fullness to the brain.
It also has the highest thermic effect of any macronutrient. Roughly twenty to thirty percent of protein energy is used in digesting and processing it, compared with around five to ten percent for carbohydrate and zero to three percent for fat. Some of what you eat is spent on eating it.
The muscle preservation argument
This is arguably more important than the appetite effect. When you lose weight, some of the loss comes from lean tissue unless you actively protect it.
Muscle is metabolically active tissue. Losing it lowers your resting energy expenditure, which makes maintaining the lower weight harder. Adequate protein, particularly combined with resistance training, substantially reduces lean tissue loss during a deficit.
How much is enough
The Australian recommended dietary intake of around 0.84 grams per kilogram for adults is set to prevent deficiency, not to optimise body composition during weight loss.
Research on protein during energy restriction generally supports higher intakes, commonly in the range of 1.2 to 1.6 grams per kilogram of body weight, and sometimes higher for older adults or those training regularly. If you have kidney disease, discuss intake with your practitioner before increasing it, as recommendations differ.
Distribution across the day matters
Most people eat very little protein at breakfast, a moderate amount at lunch and most of the day’s total at dinner. Spreading it more evenly appears to support muscle maintenance better than concentrating it in one meal.
A practical target is 25 to 35 grams at each main meal rather than 10 grams at breakfast and 60 at dinner. Breakfast is usually where the biggest change is available.
Practical sources
Approximate protein per serve, to make the target concrete.
- Chicken breast, 100g cooked: around 31g
- Greek yoghurt, 200g: around 20g
- Tin of tuna, 95g: around 22g
- Two large eggs: around 13g
- Cooked lentils, one cup: around 18g
- Firm tofu, 150g: around 17g
- Cottage cheese, 100g: around 12g
- Milk, 250ml: around 8g
Frequently asked questions
How much protein should I eat when losing weight?
Research during energy restriction commonly supports 1.2 to 1.6 grams per kilogram of body weight, which is above the recommended dietary intake set to prevent deficiency.
Why does protein keep you full?
It stimulates gut satiety hormones including peptide YY and cholecystokinin, and has the highest thermic effect of any macronutrient at twenty to thirty percent of its energy.
Does protein help preserve muscle during weight loss?
Yes. Adequate protein combined with resistance training substantially reduces lean tissue loss, which helps maintain energy expenditure.
Should I spread protein across the day?
Even distribution of roughly 25 to 35 grams per main meal appears to support muscle maintenance better than concentrating most of it at dinner.
Can you eat too much protein?
For most healthy adults higher intakes are well tolerated. People with kidney disease should discuss intake with their practitioner, as recommendations differ.