Unhealthiest Fast Food Milkshakes, Ranked

Ordering a regular milkshake with your fast food meal feels harmless enough — until you realize it might be the most over-the-top thing in the bag.

PlushCare analyzed vanilla shakes from 14 major fast food chains, breaking each one down by energy, fat, sugar, and sodium to calculate a final unhealthiness score. We also looked at the full nutritional breakdown for each shake to give you a clearer picture of what you’re actually drinking sugar and fat were the usual suspects, but a few shakes also came loaded with way more salt than you'd expect from something sweet.

Here’s how they all ranked, from the least to the most unhealthy.

Unhealthiness Score: 26

1. Energy: 6
2. Fat: 8
3. Sugar: 11
4. Sodium: 2

Mickey D serves one of the lightest shakes on the “feel guilty” scale, but don’t get too smug. A regular shake here still comes with around 62 grams of sugar, which is way more than what your dentist thinks you deserve in a day.

Unhealthiness Score: 27

1. Energy: 8
2. Fat: 2
3. Sugar: 12
4. Sodium: 5

Smashburger flies under the radar but don’t be fooled — it’s a caloric sneak attack. At 760 calories and 61 grams of sugar, it’s one of the fattiest options on the list (46 grams of fat).

Unhealthiness Score: 33

1. Energy: 5
2. Fat: 11
3. Sugar: 14
4. Sodium: 3

Arby’s shake comes with 64 grams of sugar, accompanied by a whipped topping that may look innocent but isn't. We wouldn't be mad if it came with a straw and a warning label.

Unhealthiness Score: 36

1. Energy: 6
2. Fat: 9
3. Sugar: 17
4. Sodium: 4

501 calories, 26 grams of fat, the King serves a decent shake until you remember it’s supposed to be the small size. Good luck walking upright if you pair this with a Whopper.

Unhealthiness Score: 39

1. Energy: 6
2. Fat: 9
3. Sugar: 19
4. Sodium: 5

Whataburger’s Medium Vanilla Shake contains 86 grams of sugar—a dessert-level amount without factoring in the 510 calories.

Unhealthiness Score: 41

1. Energy: 7
2. Fat: 12
3. Sugar: 20
4. Sodium: 2

This hand-dipped shake has that dense, custard-like texture people swear by—but nutritionally, it’s a red flag. With 92 grams of sugar, you’re basically downing 23 teaspoons in one go. Enough to give a sugar rush to a rock.

Unhealthiness Score: 42

1. Energy: 7
2. Fat: 17
3. Sugar: 15
4. Sodium: 3

The whipped cream and cherry make it look friendly, but it’s one of the fattiest on the list. Jack’s shakes are made from a base that leans more artificial, so you’re getting flavor over quality ingredients.

Unhealthiness Score: 43

1. Energy: 7
2. Fat:20
3. Sugar: 12
4. Sodium: 4

In-N-Out uses real ice cream, which you can tell from the thicker texture. It’s simpler and slightly more balanced than most shakes here, but it still comes with a nutritional baggageof 590 calories, 55 grams of sugar, and 31 grams of fat.

Unhealthiness Score: 44

1. Energy: 8
2. Fat:16
3. Sugar:18
4. Sodium: 2

DQ uses soft serve as the base, so it’s smooth and sweet but also aerated, meaning it’s easier to drink fast, which is not the best idea, given it has 65 grams of sugar.

Unhealthiness Score: 47

1. Energy: 8
2. Fat: 14
3. Sugar: 20
4. Sodium: 5

This shake has 900 calories and 70 grams of sugar — the highest sugar so far on the list, and half a day’s worth of calories before you’ve even had lunch.

Unhealthiness Score: 50

1. Energy: 9
2. Fat: 24
3. Sugar: 15
4. Sodium: 2

The hand-scooped shake tastes legit because it is — but it’s also one of the heaviest here, with 740 calories, 70 grams of sugar, and 36 grams of fat.

Unhealthiness Score: 51

1. Energy: 8
2. Fat: 21
3. Sugar: 18
4. Sodium: 4

Before adding any toppings, the base shake is already intense, with 670 calories and 84 grams of sugar. Add-ins like peanut butter or Oreos push it well past the 1,000 mark.

Unhealthiness Score: 55

1. Energy: 8
2. Fat: 20
3. Sugar: 20
4. Sodium: 7

This medium shake comes in at710 calories and 92 grams of sugar, with a surprising 630 milligrams of sodium. It’s a full-blown meal with a straw.

Unhealthiness Score: 63

1. Energy: 11
2. Fat: 30
3. Sugar: 19
4. Sodium: 3

Well, it’s not called Lightburger. Fatburger’s Vanilla Shake takes the crown as the worst for your health with 890 calories, 86 grams of sugar, and 44 grams of fat. It’s an absolute monster of a shake and fully owns it.