Keto Diet for Beginners: What to Eat, What to Avoid, and How to Start

The keto diet works by flipping your body's primary fuel source from glucose (carbs) to ketones (made from fat). Once you're in ketosis, your body burns fat 24/7 — including stored body fat. The trade-off: you have to keep carbs very low, usually under 20–30g of net carbs per day.

Keto macros: the only numbers that matter

For a standard keto diet, aim for:

Fat: 70–75% of calories
Protein: 20–25% of calories
Carbs: 5–10% of calories (usually 20–30g net carbs)

Net carbs = total carbs − fiber. Fiber doesn't spike blood sugar, so it doesn't count against your daily limit. This is why a cup of broccoli (6g total, 4g fiber) only "costs" you 2g net carbs.

The keto food list — eat freely

Meat: beef, chicken, pork, lamb, bacon
Fish & seafood: salmon, sardines, tuna, shrimp
Eggs: whole, in any form
Healthy fats: butter, ghee, olive oil, avocado oil, coconut oil
Low-carb vegetables: spinach, kale, broccoli, cauliflower, zucchini, asparagus, bell peppers
Full-fat dairy: heavy cream, hard cheeses, Greek yogurt (plain)
Nuts & seeds (in moderation): almonds, walnuts, macadamias, chia, flax
Avocado, olives, berries (in small amounts)

What to avoid completely

Sugar (including honey, agave, maple syrup)
Grains (wheat, rice, oats, corn, quinoa)
Starchy vegetables (potatoes, sweet potatoes, peas)
Most fruits (bananas, apples, oranges, grapes)
Legumes (beans, lentils, chickpeas)
Beer and sweet cocktails
Low-fat or "diet" anything (usually loaded with sugar)

The keto flu — and how to crush it

Days 2–7 of keto are usually the hardest. As your body switches from carbs to fat, you may feel tired, foggy, headachy, or irritable. This is the keto flu, and it's almost always caused by electrolyte loss — not a lack of carbs.

Daily during the first 2 weeks, get:

3,000–5,000mg sodium (salt your food generously, drink salted broth)
1,000mg potassium (avocado, spinach, salmon)
300–400mg magnesium (nuts, dark chocolate, or a supplement)

Most people feel dramatically better within 48 hours of fixing electrolytes.

How to know you're in ketosis

Signs you've entered ketosis (usually 2–7 days in):

Reduced hunger and cravings
Mental clarity (after the keto flu passes)
"Keto breath" — a slight fruity or metallic taste
Steady energy throughout the day
Rapid initial weight loss (mostly water in week 1)

If you want a definitive answer, urine ketone strips are cheap (~$10) and blood ketone meters are more accurate (~$30 + strips).

Realistic results

Week 1: 3–8 lbs lost, mostly water weight as glycogen empties.
Weeks 2–4: 1–2 lbs of fat loss per week, plus appetite drops noticeably.
Months 2–6: Steady 1–2 lbs/week if you maintain a calorie deficit. Keto isn't magic — you still need to eat less than you burn. It just makes that easier by killing hunger.

The bottom line

Keto works extremely well for people who do well with structure and don't mind giving up bread and sugar. It's particularly effective for type 2 diabetes, insulin resistance, and stubborn belly fat. If you're an endurance athlete or you live on fruit and oatmeal, keto probably isn't for you.

MyDietingApp has a dedicated keto mode that tracks net carbs automatically, flags hidden carbs in foods, and shows your macro split in real time. Way easier than spreadsheets.