Do you really burn up to 30% of protein calories digesting it?

Yes. This is called the thermic effect of food. Roughly 20–30% of protein calories are spent just processing it, compared with about 5–10% for carbohydrates and 0–3% for fats. A 100 kcal portion of chicken effectively delivers around 70–80 kcal — while 100 kcal of oil delivers nearly all of it.

Can I eat junk food and still lose weight if it fits my calories?

In pure energy-balance terms, yes — and small treats inside a calorie budget are fine and make a diet sustainable. The problem is that ultra-processed calories are easy to overeat: they bypass satiety signals, digest fast, and leave you hungry again quickly. Most people fail not on arithmetic but on hunger.

What is the 100-calorie myth?

The idea that a 100-calorie snack pack is a meaningful, comparable unit of food. 100 calories of cookies is a few bites that spike hunger again within the hour; 100 calories of Greek yogurt, eggs or vegetables is food that actually contributes to fullness and protein needs. The number is equal, the outcome is not.

So should I track macros instead of calories?

Track both, in that order. Calories set the budget and decide the direction of your weight; protein (and to a lesser degree fibre and food quality) decides how hungry you are and how much muscle you keep while the weight moves. A calorie target with a protein floor is the most practical version of this.

Are All Calories Created Equal? The Truth Behind the 100-Calorie Myth

Q: Are all calories created equal?

As units of energy, yes — a calorie is a calorie when it comes to the energy-balance equation that decides whether your weight goes up or down. But calories from different foods behave differently inside your body: they cost different amounts of energy to digest, trigger different fullness hormones, and support different body compositions. Equal on the label, unequal in practice.

If weight loss comes down to energy balance, does that mean 500 calories of cookies works the same way as 500 calories of salmon and sweet potatoes? Yes and no — and the "no" is where most diets quietly fail.

Watch the comparison: 200 calories of cookies versus 200 calories of whole foods.

The short version

Energy balance decides whether weight goes up or down — that part of the "a calorie is a calorie" argument is solid.
How those calories behave inside you decides how hungry, energetic and lean you stay.
Protein burns up to 30% of its own calories just being digested; fat burns almost none.
Equal calories never equal equal fullness — nutrient-dense foods trigger satiety hormones, ultra-processed foods bypass them.
Calorie counting sets the budget; macros and food quality dictate your results.

Thermodynamics vs. metabolism

A calorie is a unit of measurement — the energy needed to raise one gram of water by one degree. In that sense, 100 calories of cookies and 100 calories of chicken are identical amounts of energy, and the law of thermodynamics does not care where they came from. If you eat fewer calories than you burn, you lose weight. That is not up for debate.

But your body is not a bomb calorimeter. Your digestive system spends energy just processing what you eat — the thermic effect of food. Protein burns up to 30% of its own calories during digestion, carbohydrates around 5–10%, and fats almost nothing. Eat 300 kcal of protein and your body keeps roughly 210–240 of them. Eat 300 kcal of oil and nearly all 300 arrive. Same number on the label, different number in your body.

The satiety trap

Equal calories never equal equal fullness. Nutrient-dense foods — protein, fibre, water-rich vegetables, whole grains — stretch the stomach, slow digestion and trigger the hormones (GLP-1, peptide YY, leptin) that tell your brain you have eaten. This is one reason ultra-processed foods are so easy to overeat: they are engineered to be soft, fast and hyper-palatable, and they bypass those signals almost entirely.

This is also why 100-calorie snack packs are a trap dressed as a solution. A 100-calorie cookie pack is three bites that leave you hungrier than before. A 100-calorie portion of Greek yogurt with berries, two eggs, or a large bowl of vegetables is food that actually carries you to the next meal. The number is the same; the outcome is not.

200 calories of cookies vs. 200 calories of whole foods

The clearest way to see the myth is visually. Two hundred calories of cookies is a small handful — three to four small biscuits, gone in thirty seconds, hunger back within the hour. Two hundred calories of whole food is a plate: roughly a large chicken breast with a mountain of broccoli and a side of sweet potato, or 300 g of Greek yogurt with fruit. Same energy, wildly different volume, protein, fibre, micronutrients and fullness.

See the visual comparison

We put both plates side by side in a 30-second clip — watch the short video to see what the same calories actually look like.

The real objective

Here is the practical takeaway: calorie counting sets the budget, but macronutrients and food quality dictate your results. Two people can eat the same 1,800 kcal and have completely different experiences — one starving, lethargic and losing muscle, one full, energetic and keeping their strength. The difference is not arithmetic. It is protein, fibre and how close their food is to something that grew or lived.

Tracking is not about eating junk food to hit a number. It is about knowing your baseline so you can fuel your body intentionally — seeing that your "healthy" smoothie is 600 kcal, that your weekdays are perfect but your weekends erase the deficit, and that a protein-focused plate keeps you full on fewer calories without white-knuckle willpower.

What this means for how you track

Set a calorie target from your actual needs — the calorie calculator gives you TDEE and a macro split in seconds.
Put a protein floor under it — roughly 1.6–2.2 g per kg of body weight is the evidence-based range for keeping muscle.
Spend the remaining calories on food that fights hunger — fibre, volume, water-rich foods — not on the smallest package that fits the number.
Log honestly, including the cookies. A 500 kcal treat inside a known budget is a plan; an unlogged 500 kcal is the reason the scale stalls.
Judge results by the weekly trend, not a single day — see our guide to tracking calories properly.

For the energy-balance foundation behind all of this, read why calorie counting works and what a calorie deficit actually is.