Calorie measurement and the Atwater system

• A lower-case calorie is the energy needed to heat 1 ml of water by 1°C.
• Food energy uses kilocalories, but everyday speech often says calories when it means kilocalories.
• Modern calorie numbers come from Wilbur Atwater, bomb calorimetry, and late-1800s energy experiments.
• Atwater burned food, measured excreted energy in urine and feces, and used water-bath calorimetry on human subjects.
• The familiar factors are fat at 9 kcal/g, protein at 4 kcal/g, carbohydrate at 4 kcal/g, and alcohol at 7 kcal/g.
• Nutrition panels usually add up macronutrient grams multiplied by those factors.
• The flaw is that a human body is not a bomb calorimeter or a calculator.

Why the same listed calories can yield different usable energy

• Nutrition panels assume all fats, proteins, and carbohydrates are metabolically equivalent within their category.
• They also assume highly efficient and uniform extraction of energy from food.
• Pistachios show the problem because swallowed whole pistachios yield little usable energy, while chewed pistachios yield more.
• Mechanical processing from chewing and industrial processing from grinding, cooking, and blending change energy extraction.
• Raw foods generally yield fewer usable calories than cooked foods.
• Whole nuts generally yield fewer usable calories than nut butters.
• Chewing therefore has metabolic consequences beyond table manners.

Thermic effect and macronutrient cost

• Protein has a high thermic effect, with roughly 20-30% of its energy used during digestion and processing.
• Carbohydrate costs about 5-10% to process.
• Fat costs about 3% or less to process.
• A 100-kcal protein portion therefore delivers less usable energy than a 100-kcal fat portion.
• High-protein diets can look more effective for fat loss because digestion itself uses more energy.
• The panel still lists both as 100 kcal, even though the body handles them differently.

Overfeeding examples

• Sam Feltham's 21-day self-experiments used about 5,800 kcal/day with different macronutrient compositions.
• On low-carb, high-fat intake, weight rose from 85.6 kg to 86.9 kg, a gain of 1.3 kg, while waist fell by 3 cm.
• The traditional calorie model predicted about 6 kg more gain than the low-carb result.
• On high-carbohydrate intake, weight rose by 7.1 kg and waist rose by about 9 cm.
• On very-low-fat vegan intake, weight rose by 4.7 kg and waist rose by 7.75 cm.
• The same person and same large calorie surplus produced different outcomes by macronutrient mix.
• Layne Norton misses these studies and overfeeding examples.

Metabolic ward evidence and sugar-film example

• The Horton metabolic ward study tested fat and carbohydrate overfeeding under controlled conditions.
• Carbohydrate overfeeding stored 75-85% of excess energy as body fat.
• Fat overfeeding produced different storage patterns and different energy-expenditure effects.
• Identical calorie intake therefore did not produce identical metabolic outcomes.
• Damon Gameau's That Sugar Film experiment kept intake at about 2,300 kcal/day while swapping dietary fat for sugar.
• The 60-day sugar intake came from foods marketed as healthy, including low-fat yogurts, cereals, bars, and smoothies.
• Outcomes included 8.5 kg weight gain, 10 cm waist gain, 7% body-fat gain, fatty liver disease, and worse mood and energy.
• Some days were under 2,300 kcal, yet weight gain continued.
• After returning to the previous diet, the metabolic damage was reversed within about two months.

Negative-calorie foods, energy disposal, and low-carb context

• Celery as a negative-calorie food is mostly wishful thinking; it is close, but still net positive in ordinary use.
• Ice-cold water costs some energy to warm, but about 8 L/day would be needed for roughly 100 kcal.
• Metabolized food becomes energy, water, carbon dioxide, urine, sweat, and heat.
• Much fat loss leaves through exhaled carbon dioxide.
• In low-carb, keto, or carnivore eating, insulin stays lower and more stable, and stored fat becomes easier to access.
• Fat adaptation changes enzymes, hormone signals, fuel partitioning, and interpretation of lab ranges built from high-carb populations.
• A donut calorie and a ribeye calorie have different metabolic handling, storage, and burning patterns.
• Calorie counting is a rough guide, not a reliable master metric for human metabolism.
• The better focus is species-appropriate food, natural hunger and satiety, and the weight and quality of food.

References

• [01:21] In the Footsteps of Wilbur Olin Atwater: The Atwater Lecture for 2019 — https://doi.org/10.1093/advances/nmz128
• [04:28] Measured energy value of pistachios in the human diet — https://doi.org/10.1017/S0007114511002649
• [05:16] Energetic consequences of thermal and nonthermal food processing — https://doi.org/10.1073/pnas.1112128108
• [05:49] Diet induced thermogenesis — https://doi.org/10.1186/1743-7075-1-5
• [07:02] The 21 Day 5,000 Calorie LCHF Challenge — https://www.youtube.com/playlist?list=PLZvITiygC4TbAMvSyTnG8d1fogchxlJTP
• [09:59] Fat and carbohydrate overfeeding in humans: different effects on energy storage — https://doi.org/10.1093/ajcn/62.1.19
• [11:34] That Sugar Film — https://www.samuelgoldwynfilms.com/that-sugar-film/

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