Nutrition, explained from the evidence

Short, specific answers to the questions people actually ask about food, weight and activity. Every article is built from official guidelines (WHO, NIH, FDA, CDC, NHS, EFSA) and peer-reviewed research, every number has a source you can click, and nothing here is medical advice.

Written by the Calobook team Sources: official bodies and peer-reviewed studies only RSS feed

Calories and weight·9 min read How many calories should I eat a day? Most adult women need about 1,600 to 2,400 calories a day and most adult men 2,000 to 3,000. Here is how to estimate your own number with the Mifflin-St Jeor equation, how large a deficit is safe for weight loss, and why the target has to be retuned as you lose weight. Read the article Labels and tracking·9 min read How accurate is AI calorie counting from a photo? An honest answer A photo can estimate what it can see: the food, roughly how much, and how it was cooked. It cannot see oil absorbed in a pan, sugar in a sauce or the bottom half of a bowl. Here is what the research says about photo-based food logging, why even nutrition labels are allowed a 20 percent margin, which logging method to use when, and why a weekly weight trend fixes the errors that no estimate can. Read the article Protein and macros·8 min read How much protein do you need per day? The official minimum is 0.8 g of protein per kilogram of body weight a day, about 56 g for a 70 kg adult. People who train, are losing weight or are over 65 do better at 1.2 to 2.0 g/kg. Here is what the RDA, EFSA, the ISSN and the largest meta-analysis actually say, with a per-meal target and a food table. Read the article Labels and tracking·8 min read How to read a Nutrition Facts label in 60 seconds Serving size first, then calories, then the three lines to limit (saturated fat, sodium, added sugars) and the ones to get more of (fiber, vitamin D, calcium, iron, potassium). The 5 and 20 percent Daily Value rule, what the US, UK and EU labels do differently, and why label numbers can legally be off by 20 percent. Read the article Calories and weight·8 min read Why your weight fluctuates day to day (and how to read the trend instead) A 1 to 2 kg swing between mornings is normal and is almost never fat. Glycogen holds about 3 g of water per gram, a salty dinner adds fluid, the menstrual cycle adds more, and weekends push the scale up every week. Here is what moves the number, how to weigh so the noise is smallest, and how to read a weekly trend that actually tells you something. Read the article Nutrients and limits·7 min read How much sodium (salt) per day? WHO, FDA, AHA and NHS limits compared The WHO says under 2,000 mg of sodium a day (5 g of salt), the US Dietary Guidelines under 2,300 mg, the American Heart Association ideally 1,500 mg, and the NHS under 6 g of salt. Most people eat close to double. Here is where it comes from, how to read it on a label, and why potassium matters too. Read the article Nutrients and limits·7 min read Added sugar: how much is too much, and how to find it on a label The WHO says keep free sugars under 10 percent of calories, ideally under 5 percent (about 25 g a day). The American Heart Association says 25 g for women and 36 g for men, the UK says 30 g, and the US label Daily Value is 50 g. Here is what counts as added sugar, what does not, where it hides and how to cut it. Read the article Protein and macros·8 min read How much fiber per day? Targets, benefits and the easiest foods to hit them The US target is 14 g of fiber per 1,000 calories, about 25 g a day for women and 38 g for men; the UK says 30 g. More than 90 percent of people fall short. A 2019 Lancet review linked 25 to 29 g a day with 15 to 30 percent lower rates of death and major disease. Here is what fiber does, which foods carry the most, and how to add 10 g without noticing. Read the article Hydration and activity·8 min read How much water should you drink a day? The real numbers, not the 8-glasses rule The US reference intake is about 3.7 liters of total water a day for men and 2.7 for women, including the roughly 20 percent that comes from food. Europe's figures are 2.5 and 2.0 liters. The NHS says 6 to 8 glasses. Here is where the 8-glasses rule came from, whether coffee counts, how much is too much, and what changes with heat, exercise and kidney stones. Read the article Hydration and activity·7 min read How many steps a day do you really need? What the research says about 10,000 10,000 steps began as a 1960s pedometer slogan, not a study. The research since says the health benefit rises steeply from about 4,000 steps, keeps improving to roughly 8,000 to 10,000 for adults under 60 and 6,000 to 8,000 for those over 60, then levels off. Here is how steps map to the WHO's 150 minutes, what they burn, and how to pick a target. Read the article

Put the numbers to work

Calobook turns these guidelines into daily targets for your body, scores every meal against them, and retunes the plan each week from what you actually logged.

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