How Many Grams of Fat Per Day to Lose Weight?

Last updated: May 2026

For weight loss, the general guidance is 0.5–1g of fat per kg of body weight per day — or keeping fat at 20–35% of your reduced daily calorie intake. The most important thing to understand about fat during a cut is that going too low is just as problematic as going too high.

How to Calculate Fat Grams for Weight Loss

Two approaches — use whichever is easier:

Method 1: Percentage of calories

1. Calculate your deficit calorie target (TDEE minus 300–500 calories)
2. Multiply by your target fat percentage (20–30% for cutting)
3. Divide by 9 (calories per gram of fat)

Example: 1,600 calorie deficit target × 0.25 = 400 fat calories ÷ 9 = ~44g fat/day

Method 2: Grams per kg body weight

Use 0.5–1g of fat per kg of body weight.

Why You Shouldn’t Cut Fat Below 20% While Losing Weight

Several controlled studies show that reducing dietary fat from 30–40% of calories down to 15–25% causes significant but modest reductions in circulating testosterone in both men and women. This matters for weight loss because:

• Testosterone supports muscle protein synthesis during a calorie deficit — preserving the muscle mass that keeps your metabolism elevated
• Low testosterone relative to cortisol impairs recovery from training, reducing the effectiveness of exercise during a cut
• Fat is required for the production of steroid hormones including estrogen, testosterone, and cortisol — all of which are involved in body composition regulation

The practical floor for dietary fat during weight loss is 20% of total calories or approximately 0.5g/kg body weight — whichever is higher. Going below this increases hormonal disruption without meaningfully accelerating fat loss.

Low-Fat vs. Low-Carb: Which Loses More Weight?

Research is consistent on this: when total calories and protein are equated, low-fat and low-carbohydrate diets produce nearly identical weight loss outcomes at 12 months. A 2018 randomized controlled trial (the DIETFITS study, JAMA) found no significant difference in weight loss between low-fat and low-carb diets over 12 months when protein was sufficient.

A review in the Journal of Obesity & Metabolic Syndrome (2020) concluded the same: “it is not clear which type of macronutrient (fat or carbohydrate) restriction provides a greater advantage for weight loss.” Calorie deficit is the primary driver, not macronutrient ratio.

Choose whichever approach you can sustain. If you find lower-fat eating more filling and sustainable, go lower on fat. If higher-fat foods improve diet adherence, go higher — just stay within the 20–35% range.

What About Very Low-Fat Diets (Under 15%)?

Very low-fat diets (VLFD), defined as providing 10–20% of calories from fat, are sometimes used in clinical settings for specific conditions (cardiovascular disease, gallbladder issues). They are not recommended for people who train, as the testosterone suppression and essential fatty acid deficiency risks outweigh the marginal calorie reduction benefit. Essential fatty acid deficiency symptoms include joint pain, skin rashes, brittle hair and nails, and dry eyes.

Ketogenic Diets: High Fat for Weight Loss

Ketogenic diets flip the standard approach, with fat comprising 60–80% of daily calories. Research shows they can produce similar weight loss to conventional calorie restriction when protein is matched. The mechanism appears to be primarily appetite suppression — ketosis and very high fat intake reduces hunger hormones, leading to spontaneous calorie reduction. However, longitudinal resistance training studies consistently show inferior muscle mass gains on ketogenic versus moderate-carbohydrate diets, making keto a suboptimal choice for people whose primary goal is muscle building alongside fat loss.

Best Fat Sources for Weight Loss

When calories are limited, every gram of fat should come from foods with a good protein-to-calorie ratio and high satiety value:

• Salmon and fatty fish: high protein and omega-3 — reduce inflammation and support muscle preservation during a cut
• Whole eggs: ~5g fat each, high satiety, complete protein — cost-efficient and filling
• Avocado (½ medium): ~10g fat, also high in fiber — extends satiety from meals
• Almonds (1 oz): ~14g fat, 6g protein — portable and satiating snack
• Olive oil (for cooking): calorie-dense but a small amount adds significant flavor and satiety

Avoid high-fat processed foods (fried foods, commercial baked goods) during a cut — they provide fat and calories without meaningful protein, fiber, or satiety benefit.

Frequently Asked Questions

Is 50g of fat per day too low?

Depends on your body weight and calorie budget. For a 68 kg (150 lb) person on a 1,600-calorie cut, 50g of fat = 28% of calories — within the healthy range. For a 100 kg (220 lb) person on 2,000 calories, 50g = 22.5% — also fine but at the lower end. Calculate by percentage rather than an absolute gram number to ensure the amount is appropriate for your calorie budget.

Can you lose weight eating more fat?

Yes — calorie deficit is what drives fat loss, not how much fat you eat as a percentage. Many people successfully lose weight on diets where fat accounts for 40–50% of calories (lower carbohydrate approaches). The key is total calorie intake, not the fat percentage.