vs. Almonds, Oats, and Pistachios
More protein. Fewer calories. No nuts.
Gram for gram and calorie for calorie, watermelon seeds out-perform almonds, pistachios and oats on protein.
The Data
Every calorie on the label has to earn its place
Watermelon seeds deliver 5.09 g of protein for every 100 calories. That's 39% more protein per calorie than almonds, 41% more than pistachios, and 17% more than oats. That difference is what lets you hit a protein target without the calorie count creeping up.
What 10 grams of protein costs you
Same protein target, four different calorie bills. Each dot is 20 calories.
Watermelon seed kernel
Oats
Almonds
Pistachios
More of every essential amino acid than an almond
Not most of them. All nine. Gram for gram, watermelon seeds carry more of every essential amino acid than almonds do.
Milligrams per 100 g. USDA FoodData Central, entries 169407 and 170567.
57% more lysine, five times the methionine
Lysine is the one amino acid that sets the protein quality score for watermelon seed, almonds and oats alike. Head to head with almonds, watermelon seed carries 890 mg of lysine per 100 g against their 568 mg. Measure that same lysine per calorie instead of per gram and the gap widens further, to 160 mg against 98 mg.
Strong where nut protein is weak
Several studies put methionine and cysteine among the limiting amino acids in almond protein. Watermelon seed carries over five times the methionine and runs a clear surplus in the sulfur amino acids.
Eight of nine amino acids in surplus
Your body needs nine essential amino acids in set amounts. The bars below show how much of each one watermelon seed protein supplies, where 100% means it exactly meets an adult's requirement. Eight of the nine clear it outright. Lysine sits at 70% against almonds' 60%, scored the same way.
Percentages calculated from USDA composition against the FAO/WHO/UNU adult reference pattern. Full working in the next section.
Magnesium isn't a close race
A 30 g portion of kernels carries roughly 155 mg of magnesium, about 37% of an adult daily value.
How we calculated protein quality
Start with USDA data
Per 100 g of kernel: 28.33 g protein, plus each amino acid in milligrams. FoodData Central entry 169407.
Express per gram of protein
Divide each amino acid by 28.33. This removes protein content from the comparison so only quality is measured.
Compare to the FAO pattern
Divide by the FAO/WHO/UNU adult requirement for that amino acid. Above 1.00 means a surplus.
Take the lowest result
The score is set by whichever amino acid runs out first. Here that is lysine, at 0.70.
| Amino acid | mg per 100 g | ÷ 28.33 g protein | FAO adult need | Ratio |
|---|---|---|---|---|
| Lysine | 890 | 31.4 | 45 | 0.70 |
| Leucine | 2,150 | 75.9 | 59 | 1.29 |
| Valine | 1,560 | 55.1 | 39 | 1.41 |
| Isoleucine | 1,340 | 47.3 | 30 | 1.58 |
| Threonine | 1,110 | 39.2 | 23 | 1.70 |
| Histidine | 780 | 27.5 | 15 | 1.84 |
| Methionine + cysteine | 830 + 440 | 44.8 | 22 | 2.04 |
| Tryptophan | 390 | 13.8 | 6 | 2.29 |
| Phenylalanine + tyrosine | 2,030 + 1,020 | 107.7 | 38 | 2.83 |
Compare scores only against the same reference pattern. Run almonds through the identical four steps — USDA entry 170567, 568 mg lysine, 21.15 g protein — and almonds score 0.60 against watermelon seed's 0.70.
Do not compare this to a published PDCAAS. PDCAAS uses the stricter preschool-child pattern (lysine 58 mg/g instead of 45) and then multiplies by digestibility, so its numbers are lower by construction. On that pattern the same two foods score 0.54 and 0.46, a near-identical 17% gap, just on a lower scale. Digestibility is comparable in both (watermelon seed 76–91% in vitro; almonds 86–90% true faecal), so correcting for it narrows the gap rather than reversing it.
The scorecard
| Claim | Evidence | Winner |
|---|---|---|
| Most protein per 100 g of the four | 28.3 g vs 21.2 / 20.2 / 16.9 | Watermelon Seeds |
| Best protein per calorie of the four | 5.09 g per 100 kcal | Watermelon Seeds |
| More of every essential amino acid than almonds | All nine higher per 100 g | Watermelon Seeds |
| Higher amino acid score than almonds | 0.70 vs 0.60, same reference pattern | Watermelon Seeds |
| Highest magnesium, zinc, iron and phosphorus | 515 mg Mg, 10.2 mg Zn per 100 g | Watermelon Seeds |
| Eight of nine amino acids in surplus | 129-283% of adult requirement | Watermelon Seeds |
| Richest in arginine among common oilseeds | 4.90 g per 100 g, above soy and peanut | Watermelon Seeds |
| Not a top-nine allergen | Not a tree nut, peanut or dairy | Watermelon Seeds |
Composition. USDA FoodData Central, entries 169407 (watermelon seed kernels, dried), 170567 (almonds, raw) and 169705 (oats) — fdc.nal.usda.gov. Amino acid scores calculated against the FAO/WHO/UNU adult reference pattern.
Protein quality benchmarks. Bailey & Stein 2020, J Sci Food Agric 100:3878–3885, pistachio DIAAS — pubmed.ncbi.nlm.nih.gov/32323331. Abelilla, Liu & Stein 2018, J Sci Food Agric 98:410–414, oat protein concentrate — pubmed.ncbi.nlm.nih.gov/28573795. House et al. 2019, Food Sci Nutr, almond PDCAAS and the 0.46 USDA-derived amino acid score — ncbi.nlm.nih.gov/pmc/articles/PMC6766546.
Sulfur amino acids in almond protein. Ahrens, Venkatachalam, Mistry, Lapsley & Sathe 2005, reporting methionine + cysteine as first limiting in almond kernel protein against the FAO/WHO child pattern.
Seed protein characterisation and digestibility. Wani, Sogi, Singh & Shivhare 2011, J Sci Food Agric — pubmed.ncbi.nlm.nih.gov/20824684. Hahn, Liszka, Maksym, Nemś & Miedzianka 2025, Molecules 30(1):181 — mdpi.com/1420-3049/30/1/181.