Boost and Ensure are nearly identical for weight gain. Both brands offer high-calorie shakes in the 350 to 360 calorie range per 8-ounce serving, and neither has a clear clinical advantage over the other. The real question isn’t which brand is “better” but which specific product line you choose within each brand, since both companies sell regular, Plus, and very high calorie versions with dramatically different calorie counts.
Calorie Comparison: Plus Versions
If you’re trying to gain weight, you want the highest calorie density per bottle. Here’s how the two main weight-gain options stack up per 8-ounce serving:
- Ensure Plus: 350 calories
- Boost Plus: 360 calories
That 10-calorie difference is meaningless in practice. Drinking two bottles a day, you’d get an extra 20 calories from Boost Plus, which amounts to roughly a single bite of bread. Both products deliver enough supplemental calories to make a real difference when added on top of regular meals.
Both brands also sell standard versions (around 240 to 250 calories per serving) that aren’t designed for weight gain. If you grab the wrong one off the shelf, you’ll get significantly fewer calories per bottle. Look specifically for the “Plus” label or, if available, the “Very High Calorie” versions, which can pack 530 calories into a single serving.
How Much Weight Can You Expect to Gain?
A multicenter study of malnourished older adults in nursing homes tracked what happens when people drink two bottles of a high-calorie, high-protein supplement daily for 12 weeks. On average, participants gained 2.6 kilograms (about 5.7 pounds), representing a 5.2% increase in body weight. Their BMI increased by about 1 point, and their nutritional status scores improved significantly.
That study reflects people who were already struggling to eat enough, which is the situation these supplements are designed for. If you’re underweight, recovering from illness, or simply can’t eat enough solid food, adding one or two high-calorie shakes per day on top of your meals can produce steady, measurable weight gain over a few months. The key phrase is “on top of.” These supplements work best as additions to your diet, not replacements for meals.
What Actually Matters for Weight Gain
Since the two brands are nutritionally so similar, your decision should come down to practical factors that determine whether you’ll actually stick with drinking them every day.
Taste. This is the single biggest factor. A supplement you don’t enjoy drinking is one you’ll skip. Both brands come in chocolate, vanilla, and strawberry, along with a few other flavors that rotate by product line. Buy a small quantity of each and see which one you prefer. Many people find one brand noticeably better-tasting than the other, but there’s no consensus on which. It’s genuinely personal.
Price. Boost and Ensure are competitively priced, but sales, store brands, and bulk pricing on sites like Amazon can shift the cost significantly. If you’re drinking two bottles a day, even a small per-bottle savings adds up over weeks. Check unit prices rather than package prices, since bottle sizes and pack counts vary.
Texture and sweetness. Some people find one brand thicker or sweeter than the other. If you’re sensitive to overly sweet drinks, try serving them chilled or over ice, which tones down the sweetness. You can also blend them into smoothies with peanut butter, banana, or oats to boost the calorie count even further while masking any flavor you don’t love.
Maximizing Calories Beyond the Bottle
Drinking a 350-calorie shake is helpful, but if weight gain is your goal, you can push each serving further. Blending a bottle of Ensure Plus or Boost Plus with two tablespoons of peanut butter and a banana turns a 350-calorie drink into roughly a 600-calorie shake. Adding full-fat yogurt, avocado, or a scoop of protein powder works too. The base shake becomes a convenient calorie vehicle rather than your only strategy.
Timing matters as well. Drinking a supplement between meals or as a bedtime snack avoids the problem of filling up before your next real meal. If you drink one right before lunch, you’ll likely eat less solid food, and the net calorie gain shrinks. Spacing your shakes at least an hour away from meals gives you the best chance of keeping your overall intake high.
Who Each Brand Might Suit Better
Both Ensure and Boost are gluten-free and suitable for lactose intolerance in most of their product lines, though you should always check the specific label since formulations change. Ensure tends to offer a slightly wider range of specialized products (such as options designed for people with diabetes or those needing extra fiber), while Boost has focused on simplicity with fewer but clearly differentiated tiers.
If you need a very high calorie option and want maximum calories per sip, Boost Very High Calorie (530 calories per 8-ounce serving) is one of the most calorie-dense commercial supplements available. Ensure doesn’t currently match that in a single product. For most people, though, the Plus versions of either brand paired with calorie-rich foods will get the job done.
The honest answer: pick whichever one tastes better to you, costs less at your local store, and comes in a flavor you won’t get tired of after two weeks. The nutritional differences are too small to matter. Consistency is what drives weight gain, and consistency depends on choosing something you’ll actually drink every day.