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EVIDENCE LIBRARY

Nutrition & health
evidence reviews

Plain-language walk-throughs of the numbers behind everyday nutrition questions. Each review traces the commonly cited guidelines back to their sources. Educational only, never a substitute for your clinician.

OUR STANDARDPeer-reviewed sources · commonly cited guidelines · 66 reviews and counting
A person cooking rice in a large pot with steam rising, next to two baking sheets of roasted chicken and vegetables and a row of empty meal-prep containers on a kitchen counterNewest review
Food reference

7-Day High Protein Meal Plan (Sample Menu)

This meal plan lays out 7 days of high protein breakfasts, lunches, dinners and snacks, with sample macros, vegetarian swaps, and a weekly grocery list.

25 min read
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All evidence reviews

Newest first. Every guideline figure links back to the review that explains it.

A man in athletic clothing on a dirt trail, pausing to drink water from a bottle after exerciseEvidence review

High Protein Diet for Muscle Gain: How It Works

This evidence review explains how a high protein diet supports muscle gain, with a protein target range, sample meals,...

25 min read
Overhead bowls of protein, carbohydrate, and fat foods on a light blue table: grilled chicken, lentils, yogurt, cubed tofu, chickpeas, avocado, sweet potato, and whole wheat breadEvidence review

High Protein Diet for Weight Loss: How It Works

This evidence review explains how a high protein diet supports weight loss, with sample meals, macros by calorie...

25 min read
A dark twin-bell alarm clock on a wood nightstand in a dim bedroom, hands positioned near ten and two, with a bed visible behind itEvidence review

Intermittent Fasting Explained: Schedules and the Evidence

Intermittent fasting explained: the 16:8, 5:2, and alternate-day schedules, what research shows on weight loss versus...

26 min read
Two people seated across a wooden table, one in a white coat writing in a spiral notebook and one in a beige sweater listening, with a bowl of bananas, an orange and apples on the table and a potted plant against a green wall behind themEvidence review

Vitamin D Deficiency Symptoms: What They Can Mean

Vitamin D deficiency symptoms are commonly linked to fatigue, bone and muscle aches, and mood changes, though none...

26 min read
An overhead arrangement on a pale surface of four brown eggs in a dark teal bowl, two teal bowls of round pale chickpeas, a pale block of tofu on a cream dish, a small teal bowl of dark red kidney beans, a scatter of almonds, walnut halves and cashews, a small teal bowl of thick white yogurt, and a raw skinless chicken breast on a cream oval plateEvidence review

How Much Zinc per Day? Daily Targets by Age and Sex

This evidence review covers how much zinc per day the reference figures describe, why they split by age and sex,...

40 min read
Two hands holding a small white carton and pointing at a printed Nutrition Facts panel whose heading is legible but whose rows of figures are too small and soft to read, against a pale green kitchen backgroundEvidence review

Calories in Peanut Butter: Per Tablespoon and Serving

This evidence review prices the calories in peanut butter: near 95 in a level tablespoon, 190 in a two tablespoon...

40 min read
An overhead arrangement on a pale surface of six pale ceramic bowls holding small brown cooked lentils, dark green spinach leaves, round pale yellow chickpeas, flat green hulled pumpkin seeds, bright orange dried apricot halves, and cubed white tofu, beside a halved orange, three lemon wedges, and a sliced cooked brown meat joint on a wooden board with a teal cloth at the right edgeEvidence review

How Much Iron per Day? Daily Targets by Age and Sex

This evidence review covers how much iron per day reference figures describe, why they split by age and sex, heme...

42 min read
A bowl of thick white yogurt topped with berries and seeds beside a glass of a white drink and a plate of scrambled eggs with wilted greensEvidence review

How Much Protein in Greek Yogurt? Per Cup and Container

This evidence review answers how much protein in Greek yogurt: about 23 grams in a cup, 15 in a small container, and...

33 min read
A carton of brown eggs beside clear bags of dried dark red beans, small pale green pulses and large white beans, with several small unlabelled tins and a tub on a wooden tableEvidence review

How to Eat Healthy on a Budget (8 Steps)

This evidence review turns eating healthy on a budget into arithmetic you can run: cost per serving, cost per gram of...

40 min read
Five drinks lined up on a pale surface beside a window: a glass of clear liquid, a small glass mug of dark brown liquid, a glass of opaque orange liquid, a tall glass of very dark liquid with a little foam at the top, and a slim aluminium can printed in bright pink, blue, green and yellowEvidence review

How Much Caffeine per Day Is Safe? Daily Limits

This evidence review covers how much caffeine per day is commonly cited as safe for adults, why that figure is a...

37 min read
Two glasses and eight small pale bowls arranged on a cream surface and seen from above: a tall glass of opaque white liquid, a shorter glass of a paler cream-coloured liquid, two bowls of thick white liquid, a bowl of pale cream-coloured cubes, a bowl of chopped dark green leaves, two bowls of leafy greens with pale stems, a bowl of small pale beans and a bowl of small silvery fishEvidence review

Milk Calories: How Many Calories in a Glass of Milk by Type

Milk calories by type: how many calories in a glass of milk, typical values for whole, 2%, 1% and skim, why plant...

39 min read
An overhead spread on a pale blue-grey surface: a bowl of white tofu cubes, a browned grilled chicken breast on a square wooden board, an orange-pink fish fillet on a wooden board, a bowl of halved hard-boiled eggs, a bowl of small brown legumes, a bowl of plain white yogurt and a bowl of small green beansFood reference

Foods High in Omega-3: A Practical List

This food reference sorts foods high in omega-3 by group, separates the plant ALA form from the marine EPA and DHA,...

38 min read
An overhead arrangement of seven dishes on a pale wooden surface holding cubed white tofu, a bowl of cooked brown or green lentils, a bowl of cooked red lentils or another split orange pulse, a small bowl of round yellow legumes, bright green shelled edamame, black beans, and an oval dish of overlapping pale slices of a firm mottled blockEvidence review

How Much Magnesium per Day? Daily Targets

This evidence review covers how much magnesium per day reference figures describe, why they rise with age, the foods...

39 min read
An overhead arrangement on a pale surface of four brown eggs in a dark teal bowl, two bowls of round golden legumes that look like chickpeas, a bowl of dark red kidney-shaped beans, a pale firm white block on a cream dish, a small bowl of thick white yogurt, a loose scatter of mixed nuts including almond-shaped kernels, walnut halves and curved cashew-shaped kernels, and a raw pale pink boneless breast fillet on an oval plateEvidence review

How Much Vitamin B12 per Day? Daily Targets

This evidence review covers how much vitamin B12 per day reference intakes describe, why the source matters more than...

37 min read
An overhead arrangement of pale ceramic bowls on a cream surface holding a glass of milk, a second glass of cream-colored liquid, two bowls of thick white yogurt, chopped dark leafy greens, pale cubes of tofu, two bowls of pale-stemmed leafy greens, white beans and small silver-skinned fishFood reference

Foods High in Calcium: A Practical List

This food reference lists foods high in calcium by group, with illustrative milligrams per serving, plus the...

40 min read
An overhead spread on a pale table: a raw salmon fillet on white parchment, a bowl of whole brown mushrooms, three brown eggs beside a cracked shell holding a yolk, a glass of milk, a plain unlabeled carton, a bowl of cereal flakes, an open tin of small silvery fish and a sage green clothEvidence review

How Much Vitamin D per Day? Daily Targets

This evidence review covers how much vitamin D per day adults need, the 600 IU and 15 mcg conversion, the short food...

42 min read
Five whole dark pebbly-skinned avocados on a pale surface beside one avocado cut in half with the pit still in it, a wedge, and three slices fanned out, with a teal cloth to the sideEvidence review

Calories in an Avocado (Half, Whole, and Sliced)

This evidence review answers how many calories are in an avocado: about 240 in a whole medium, 120 in a half and 30 in...

38 min read
A digital kitchen scale on a pale counter holding a bundle of dry long pasta strands, beside a white bowl of cooked pasta, an empty glass measuring cup, three small red tomatoes and a sprig of green leavesEvidence review

Calories in Pasta (Dry, Cooked, by Portion)

This evidence review sorts calories in pasta by dry and cooked weight, near 200 per 2 oz dry portion, plus whole...

36 min read
An overhead spread of small bowls on a pale table holding brown lentils, spinach leaves, chickpeas, green pumpkin seeds, dried apricots and white tofu cubes, beside a halved orange, lemon wedges and a sliced cooked beef roast on a wooden boardFood reference

Foods High in Iron: A Practical List

This food reference lists foods high in iron by group, with illustrative milligrams per serving, plus the pairings...

38 min read
An overhead arrangement of fat-rich whole foods on a pale green surface: a small glass cruet of golden oil, half an avocado with the stone still in it, a bowl of walnuts and almonds, a raw salmon-coloured fish fillet, four green olives, and a spoon of pale nut butterEvidence review

How Much Fat per Day? Grams by Calorie Target

This evidence review answers how much fat per day, turning the commonly cited 20 to 35 percent of calories into real...

36 min read
An overhead spread of potassium-rich foods in white bowls on a pale table: a split baked potato with its skin on, a bunch of yellow bananas, cooked white beans, wilted dark leafy greens, dried apricot halves, red tomato sauce, a glass of milk and a raw salmon fillet on parchmentEvidence review

How Much Potassium per Day? Daily Targets

This evidence review covers how much potassium per day adults need, the 3,400 and 2,600 mg adequate intakes, sources...

42 min read
An overhead arrangement on a pale mint surface of an open can of vegetable soup, a stack of white sandwich bread slices on a wooden board, folded slices of pink deli meat, a wedge of pale yellow cheese, a small bowl of dark sauce, a bowl of red tomato sauce, an open can of green beans and a small bowl of coarse white saltEvidence review

How Much Sodium per Day? Daily Limits

This evidence review covers how much sodium per day adults aim for, the commonly cited 2,300 and 1,500 mg figures, and...

41 min read
A plate of grilled poultry, mixed vegetables and grains on a kitchen counter beside a digital scale and a glass of waterEvidence review

What Is a Calorie Deficit? How to Set One Safely

This evidence review explains what a calorie deficit is, how energy balance creates one, why deficit size matters more...

30 min read
Broccoli, lettuce, carrots, apples, a pear, oranges, avocados, sweet potato and raspberries arranged togetherDigestive health

High Fiber Foods for Constipation During Pregnancy

Constipation in pregnancy is common and often iron-related: this evidence review covers the high fiber foods that...

25 min read
Bowls of cottage cheese, mixed nuts, edamame and Greek yogurt beside two halved hard-boiled eggsEvidence review

High Protein Snacks: 40+ Ideas by Protein Count

High protein snacks that actually satisfy: this evidence review lists 40 plus ideas by category, with illustrative...

25 min read
A close-up arrangement of fresh produce on a pale surface, with two red apples in front beside raspberries, a pear, oranges, avocados, carrots, broccoli, and leafy greensEvidence review

Calories in an Apple: 95 in a Medium, by Size

This evidence review answers how many calories are in a medium apple: about 95, with 77 in a small and 116 in a large,...

27 min read
Stacked clear containers packed with portioned grains, vegetables and protein on a bright kitchen counter, ready for the weekEvidence review

Back-to-School Lunch Nutrition: Balanced Lunches Kids Eat

This evidence review covers back-to-school lunch nutrition: balanced lunch builds with illustrative calorie and...

28 min read
A close arrangement on a pale surface of a broccoli head, loose leafy green lettuce and a bunch of darker greens, whole carrots, two red-skinned apples, one green pear, three round orange citrus fruits, two dark green avocados, five red raspberries and a cut root vegetable showing pale orange fleshEvidence review

How Much Vitamin C Per Day? RDA and Recommended Daily Intake

How much vitamin C per day? This evidence review sets out the RDA and recommended daily intake by age, sex and life...

44 min read
Bowls of plant proteins on a light surface: tofu, red and green lentils, chickpeas, black beans, peanut butter, seeds, and cashewsEvidence review

How to Get Protein Without Meat (Vegetarian and Vegan)

This evidence review shows how to get protein without meat: plant sources with commonly cited gram figures, honest...

33 min read
A colorful spread of fresh vegetables and fruit on a light table including carrots, sweet potato, leafy greens, apples, and berriesFood reference

Calories in a Potato: Baked, Boiled, Mashed, and Fries

This food reference breaks down the calories in a potato: near 160 in a medium baked potato and 90 per 100g, plus...

30 min read
An overhead contrast on a light table of whole-food carbs like brown rice, oats and whole grain bread on one side and refined carbs like white rice, white bread and a pastry on the otherEvidence review

Calories in Bread: Per Slice, White vs Whole Wheat

This evidence review breaks down the calories in bread: near 75 to 80 per slice of white, about 80 for whole wheat,...

30 min read
A glass of water beside a bowl of oatmeal topped with berries on a light table with a pitcher of water behindNutrition review

Calories in Oatmeal: Cooked Cup, Dry Half Cup, Packet

This nutrition review breaks down the calories in oatmeal: near 150 in a half cup of dry oats and 165 in a cooked cup,...

30 min read
An assortment of protein foods on a light table: grilled chicken, salmon, boiled eggs, lentils, tofu, yogurt, and edamameEvidence review

How Much Protein in Tuna? Canned, Fresh, and per Can

This evidence review breaks down how much protein is in tuna: near 20g per 100g of drained light tuna, about 22g in a...

30 min read
Two fresh skinless chicken breasts on a light wooden cutting board in a bright clean kitchenEvidence review

How Many Calories in Chicken Breast? (By Size)

Calories in chicken breast run near 140 per 3 oz and 165 per 100g cooked (USDA), scaled by portion size, skinless vs...

32 min read
An assortment of whole grains in bowls on a light surface, including brown rice, beside whole grain bread and a sweet potatoEvidence review

How Many Calories in Rice? (White vs Brown)

This evidence review breaks down the calories in rice by USDA portion, near 205 in a cooked cup and 130 per 100g, plus...

33 min read
A cooked salmon fillet beside grilled chicken, tofu, hard-boiled eggs, lentils, Greek yogurt and edamame in bowlsEvidence review

How Much Protein in Salmon? (By Portion)

This evidence review answers how much protein in salmon, with USDA-based figures per 3 oz, per 100g, and a fillet,...

30 min read
A whole banana beside a bowl of yogurt with berries, an apple, a bowl of oats, and a glass of water on a light surfaceEvidence review

How Many Calories Are in Bananas? 105 in a Medium

This evidence review answers how many calories are in bananas: about 105 in a medium, 72 in an extra small and 135 in...

33 min read
Fresh whole eggs on a light kitchen counter beside one cracked open to show a bright golden yolkEvidence review

How Many Calories in an Egg? 72 in a Large, by Size

Calories in an egg run about 72 in a large one, 54 in a small and 90 in a jumbo (USDA), plus how the white, yolk, and...

37 min read
A colorful spread of fresh vegetables and fruit on a light surface: broccoli, carrots, a cut orange root vegetable, leafy greens, two apples, a pear, oranges, two avocados, and raspberries, the kind of high fiber foods for constipation often discussedDigestive health

High Fiber Diet for Constipation: High Fiber Foods That Help

High fiber diet for constipation: the high fiber foods for constipation most discussed, how fiber and water work...

28 min read
An overhead spread of water-rich whole foods on a light table: watermelon, cucumber slices, orange slices, a chilled soup, and a mug of teaFood reference

High-Fiber Foods List: A Complete Reference by Group

This high-fiber foods list ranks legumes through seeds by group, with illustrative grams per typical serving and how...

33 min read
Whole-food protein sources on a light surface: tofu cubes, a grilled fillet, an orange fish fillet, halved boiled eggs, lentils, white yogurt, and green beansNutrition review

What Is a Protein Shake? How to Use Protein Shakes Well

Protein shake basics: what a protein shake is, how much protein is in one, how to use protein shakes well, when to...

28 min read
An overhead spread of water-rich whole foods on a light table: watermelon, cucumber slices, orange slices, a chilled soup, and a mug of teaEvidence review

Calories in Common Foods: A Quick Reference

This evidence review lists commonly cited calories in common foods, from a banana near 105 and an egg near 72 across...

33 min read
Apples, a pear, orange citrus fruit, raspberries, avocados, carrots, broccoli, leafy greens and a cut orange-fleshed root vegetable on a pale surfaceEvidence review

Low Calorie Snacks: 40+ Filling Ideas Under 200 Calories

Low calorie snacks ranked by grams of food per 100 calories: this evidence review prices 40 plus filling ideas and the...

53 min read
A blank notepad and pencil beside a reusable shopping bag holding fresh vegetables, a chicken breast, a tray of eggs, and a bag of grains on a light kitchen counterEvidence review

How to Build a Healthy Grocery List (7 Steps)

This evidence review is a step-by-step walkthrough for how to make a healthy grocery list, from planning meals to...

28 min read
A glass of water being filled from a carafe on a bright kitchen counterEvidence review

How to Stay Hydrated (Daily Water Guide)

This evidence review covers how to stay hydrated day to day: a simple routine, the urine-color check, water-rich...

29 min read
A balanced plate of salmon, a whole grain, and vegetables beside a glass of water on a light kitchen tableReference

Daily Nutrient Intake Reference for Adults

A one-page reference for adult daily intake: protein, fiber, water, sodium and carbohydrate values from the National...

4 min read
A reusable water bottle on a desk beside a keyboard and a plant, standing in for everyday water measurementReference

How Much Does a Gallon of Water Weigh? Pounds and Kilograms

This reference explains how much a gallon of water weighs, how many ounces and water bottles are in a gallon, and how...

28 min read
An overhead view on a bright kitchen counter of several packaged foods turned to show their nutrition panels next to a small pile of white sugar cubes and a teaspoon, calm and clean in soft teal natural lightEvidence review

How to Spot Hidden Sugar on Food Labels

This evidence review shows how to find added sugar on labels, reading the Added Sugars line, converting grams to...

28 min read
An open blank notebook and pen beside a warm drink on a wooden table, ready for a day of loggingEvidence review

How to Count and Calculate Your Macros (7 Steps)

This evidence review covers how to count macros and how to calculate your macros in one method, from setting gram...

29 min read
An overhead view of a clean white plate arranged with protein-rich whole foods: grilled chicken breast slices, soft-boiled eggs, a scoop of green peas or lentils, a small bowl of plain yogurt, and cubes of tofu on a bright light tableEvidence review

How to Eat More Protein (8 Easy Ways)

This evidence review covers how to eat more protein: a rough daily target, swaps for higher protein breakfasts and...

31 min read
An overhead view of one colorful balanced dinner plate: half filled with roasted and raw vegetables and a little fruit, a quarter with grilled chicken, and a quarter with a whole grain and cubed sweet potato, with olive oil and avocado to the sideEvidence review

How to Build a Balanced Meal (6-Step Plate Method)

This evidence review is a step-by-step walkthrough that shows how to build a balanced meal with the plate method, so...

27 min read
Several glass meal-prep containers on a clean kitchen counter, each filled with a balanced portion of grilled chicken, brown rice, broccoli, cherry tomatoes and leafy greens, in fresh natural daylightEvidence review

How to Meal Prep for the Week (7 Steps)

This evidence review is a step-by-step walkthrough that shows how to meal prep for the week, from planning a balanced...

27 min read
A person standing in a grocery store aisle holding a food package and reading the nutrition information printed on the back panel, calm and focused, in soft fresh natural lightEvidence review

How to Read a Nutrition Label (7 Steps)

This evidence review is a step-by-step walkthrough for reading a nutrition label, so you can quickly decode serving...

27 min read
An overhead spread of carbohydrate foods on a white surface: bowls of rolled oats and other flaked and cracked grains, slices of brown bread, a green apple, two bananas, blueberries, raspberries, strawberries, a carrot, two dark green cucumber-shaped vegetables, leafy greens, and a bowl of round tan legumesEvidence review

How Many Carbs Per Day? Daily Grams by Calorie Level

Daily carb intake in grams: roughly 225 to 325 g at 2,000 calories, or 45 to 65 percent of calories, with full tables...

59 min read
A balanced protein-rich meal of chicken, salmon, eggs, yogurt, lentils, and greens on a clean white plateNutrition review

How Much Protein Per Meal Can Your Body Use?

This evidence review explains how much protein per meal your body can use: you absorb nearly all of it, while...

26 min read
Raw ground beef mince beside browned cooked ground beef on a light wooden cutting board in a bright clean kitchenEvidence review

How Much Protein Is in Ground Beef?

This evidence review answers how much protein in ground beef, with figures per 100g, per ounce, by lean ratio, raw...

29 min read
Two fresh skinless chicken breasts on a light wooden cutting board in a bright clean kitchenEvidence review

How Much Protein Is in a Chicken Breast?

This evidence review answers how much protein is in chicken breast, with commonly cited figures per 100g and per 4, 6...

26 min read
Fresh whole eggs on a light kitchen counter beside one cracked open to show a bright golden yolkEvidence review

How Much Protein in Eggs? Hard-Boiled, 2 Eggs, 3 Eggs

This evidence review answers how much protein in eggs: about 6 grams per large egg, with figures for a hard-boiled...

30 min read
A stack of white sugar cubes and a teaspoon heaped with white granulated sugar beside a tall glass of a dark iced drink, with a red apple, a green apple, an orange and a few small dark and red berries on the other side of a pale tableEvidence review

How Much Sugar Per Day? Grams, Limits, Daily Intake

Evidence review of the amount of sugar recommended per day: 25 g for women and 36 for men from the AHA, under 10...

45 min read
An overhead spread of high-fiber whole foods on a light table: bowls of beans, lentils and chickpeas, a bowl of grains, blueberries, an apple and a pear, broccoli, carrots and leafy greensEvidence review

How Much Fiber Do You Need Per Day?

This evidence review lays out the commonly cited daily fiber guidance, near 25 grams for women and 38 for men, why...

27 min read
An overhead spread of protein-rich whole foods on a light table: eggs, chicken, salmon, yogurt, beans, lentils, tofu, and nutsEvidence review

High Protein Foods List: Eggs, Chicken, Beans and More

This evidence review lists high protein foods with commonly cited figures, from 2 eggs and 100g of chicken to yogurt,...

32 min read
A balanced plate of whole foods with a glass of water on a light wood tableEvidence review

How Many Calories Do You Actually Need Per Day? The Evidence

This evidence review explains what a daily calorie need is, how resting metabolism and activity combine into a total,...

26 min read
A balanced meal of salmon, eggs, lentils, and leafy greens on a light tableNutrition review

How Many Grams of Protein Do You Actually Need Per Day?

This evidence review covers how many grams of protein you need per day: the commonly cited baseline per kilogram, and...

26 min read
A calm bedroom at dawn with soft morning light and teal accent pillows on a neatly made bedEvidence review

How Many Hours of Sleep Do Adults Need? 8-Hour Rule Checked

How many hours of sleep do adults need? This evidence review traces the 7 to 9 hour range, how needs shift with age,...

28 min read
A glass of water being filled from a carafe on a bright kitchen counterEvidence review

How Much Water Should You Drink a Day? The 8 Glasses Myth

This evidence review answers how much water you should drink a day: where 8 glasses came from, what reference intakes...

27 min read