Fit Nutrition library

Nutrition Guides

Clear, practical nutrition guides that turn everyday food questions into simple decisions — how much protein you actually need, what to eat before a workout, how to read a label, and which choices are worth your attention. Every guide is written in plain language and backed by trusted sources, so you can act on it the same day.

143 guides

All guides

Ultra Processed Foods: the Government Has No Definition, and Said SoFoods & Nutrients

Ultra Processed Foods: the Government Has No Definition, and Said So

No official US definition exists — the FDA says so, and the 2026 guidelines say avoid it anyway. The real CDC numbers, and the federal limits that do exist.

17 min read
Foods High in Magnesium, and the Two That Actually QualifyFoods & Nutrients

Foods High in Magnesium, and the Two That Actually Qualify

The complete NIH table of 30 magnesium foods, adult RDAs, why the supplement limit sits below them, and the claims no federal source supports.

15 min read
Foods High in Potassium, and Why the Banana Is 10thFoods & Nutrients

Foods High in Potassium, and Why the Banana Is 10th

The full NIH table of 39 potassium foods in order, adult intake targets, why %DV understates them, and the people for whom high-potassium advice is reversed.

14 min read
High Protein Snacks, and the Part Most Lists Get WrongFoods & Nutrients

High Protein Snacks, and the Part Most Lists Get Wrong

Most Americans already hit their protein target: 88% miss seafood, 83% miss beans. What to snack on instead, and the five-second label test for any packet.

9 min read
Healthy Snacks for Weight Loss: What the Evidence SupportsMindful Eating

Healthy Snacks for Weight Loss: What the Evidence Supports

Federal reviewers found overall snacking may not be linked to weight. What that means for the portion, the label, the 300-calorie budget and the evening bag.

11 min read
Chia Seeds Benefits: What Holds Up, and What Doesn’tFoods & Nutrients

Chia Seeds Benefits: What Holds Up, and What Doesn’t

One tablespoon gives 4.1 g of fiber against a 28 g Daily Value. The omega-3 story is weaker: NIH puts ALA conversion under 15%. What chia really does.

9 min read
Brazil Nuts Benefits, and Why One Nut Is Usually EnoughFoods & Nutrients

Brazil Nuts Benefits, and Why One Nut Is Usually Enough

One Brazil nut holds 68-91 mcg of selenium against a 55 mcg daily target and a 400 mcg ceiling. What selenium does, and the four claims NIH will not back.

10 min read
Flour Substitute: How Much Almond, Oat or Coconut to UseFoods & Nutrients

Flour Substitute: How Much Almond, Oat or Coconut to Use

Almond flour replaces at most 25% of the wheat flour, coconut 20%, whole wheat 50%. The maximum shares, the fixes each needs, and why 1:1 does not work.

9 min read
Iron-Rich Foods for Anemia: What Food Can and Cannot DoFoods & Nutrients

Iron-Rich Foods for Anemia: What Food Can and Cannot Do

Which foods carry heme and non-heme iron, what raises and lowers absorption, the 1.8x plant-based adjustment, and the safety limits most lists leave out.

12 min read
Egg Substitute for Baking: Ratios That Actually WorkFoods & Nutrients

Egg Substitute for Baking: Ratios That Actually Work

One egg = 1 Tbsp ground flaxseed + 3 Tbsp water, or 1/4 cup applesauce. The ratios by function, the three-egg ceiling, and what each swap costs in protein.

10 min read
Complete Protein Foods: The List and What Incomplete MeansFoods & Nutrients

Complete Protein Foods: The List and What Incomplete Means

Which foods carry all nine essential amino acids, which fall short and in what, and why you no longer need to pair incomplete proteins at one meal.

10 min read
Plant Protein vs Whey Protein: Which Builds More Muscle?Protein

Plant Protein vs Whey Protein: Which Builds More Muscle?

Whey has more leucine and deeper research; soy is the complete plant protein; pea and rice complement each other. What differs, and how to close the gap.

12 min read
Protein Powder for Muscle Gain: What Works, How Much, and Which TypeProtein

Protein Powder for Muscle Gain: What Works, How Much, and Which Type

How much protein muscle gain needs, whether you need powder at all, whey vs casein vs plant, the 20–40 g dose, why timing barely matters, and label checks.

13 min read
Electrolyte Drinks Without Sugar: Options and a Simple Homemade RecipeHealthy Eating

Electrolyte Drinks Without Sugar: Options and a Simple Homemade Recipe

When you need electrolytes and when water is enough, what to check on a sugar-free label, and a homemade recipe with sodium and potassium from USDA data.

11 min read
High-Protein Breakfast Ideas: 20 Meals With at Least 20 g ProteinHealthy Eating

High-Protein Breakfast Ideas: 20 Meals With at Least 20 g Protein

Twenty breakfasts that each clear 20 g of protein, with the grams counted and shown - plus no-cook options and how long each one keeps in the fridge.

12 min read
High-Protein Vegetarian Foods: 30 Sources Ranked by Protein per ServingMacronutrients

High-Protein Vegetarian Foods: 30 Sources Ranked by Protein per Serving

Thirty vegetarian protein sources ranked by protein per serving, with calories alongside, so you can see what each one actually costs you to eat.

10 min read
Vitamin D Deficiency: Symptoms, Who Is at Risk and How to Fix ItVitamins & Supplements

Vitamin D Deficiency: Symptoms, Who Is at Risk and How to Fix It

Vitamin D deficiency symptoms the NIH recognizes vs the ones circulating online, who is at risk, what a 25(OH)D test means, and how to fix a low level safely.

10 min read
Protein Shake for Breakfast: What It Does for Fullness, Weight and MuscleMacronutrients

Protein Shake for Breakfast: What It Does for Fullness, Weight and Muscle

What a protein shake for breakfast does for fullness, weight and muscle, how much protein to use, whey vs plant, the added-sugar trap and who should skip it.

9 min read