Optimum Nutrition Amino Energy

Optimum Nutrition Essential Amino Energy — 5g Aminos, 100mg Caffeine, 10 Calories

Amino Energy is the most flexible product Optimum Nutrition makes. 5g of amino acids for recovery support and 100mg of naturally sourced caffeine for energy and focus, at around 10 calories per serve with no sugar. Pre-workout, mid-afternoon, or instead of a third coffee. In stock at TopDog Nutrition.

Why It Doesn't Fit One Category

Most supplements have one job and one time slot. Amino Energy deliberately doesn't, and that's the point.

At 100mg of caffeine it's a light pre-workout — roughly one coffee, enough to lift a session without the 200mg+ hit of a dedicated formula. At 5g of aminos it's an intra-workout sipper. At 10 calories with no sugar it's a genuinely reasonable all-day drink, which is how a lot of people actually use it: instead of the afternoon energy drink, at a desk, on a long drive.

That versatility is why it's one of the best-selling supplements in the world. It's not the strongest anything — it's the one that fits wherever you need it.

The 5g Amino Blend

Amino acids are the building blocks of protein, and during hard or fasted training the body will break down muscle tissue to access them. Supplying free-form aminos gives it another source to draw on.

The blend includes branched-chain amino acids — leucine, isoleucine and valine — alongside other essential and non-essential aminos. Free-form means they're already broken down, so absorption is fast, with no digestion required. That's why it works during a session where a protein shake would sit heavily.

To be straight about it: if you're already eating plenty of protein across the day, the recovery benefit of 5g of aminos is modest. Where it genuinely earns its place is fasted training, long sessions, or days when protein intake is falling short.

100mg of Naturally Sourced Caffeine

From green tea and green coffee rather than added as caffeine anhydrous. Around one coffee's worth — deliberately moderate so you can have a serve at 10am and another at 2pm and still be well under a sensible daily limit.

Caffeine from plant sources tends to feel slightly smoother, partly because it arrives with the other compounds naturally present in the leaf and bean.

10 Calories, No Sugar

The calorie count is what makes it an all-day option rather than a training-only one. A standard energy drink runs 100–200 calories with 25–50g of sugar. Amino Energy gives you the caffeine and a flavoured drink for around 10 calories and no sugar at all.

If you're cutting, or just conscious of liquid calories, that difference across two drinks a day is meaningful.

Amino Energy or Amino Energy + Electrolytes?

Same amino and caffeine base. Amino Energy + Electrolytes adds sodium, potassium and magnesium for hydration support.

Take the electrolyte version if you sweat heavily, train in heat, do long sessions, or want one drink covering energy, aminos and hydration. Standard Amino Energy is the simpler, usually cheaper option if hydration isn't the gap you're filling.

Directions

Mix 2 scoops with 300–400ml of cold water.

• Pre-workout: 20–30 minutes before training.
• Intra-workout: sipped through the session.
• Anytime: as a low-calorie flavoured caffeine drink through the day.

You can take more than one serve daily, but count your caffeine — two serves is 200mg. Avoid within 6 hours of bed.

Frequently Asked Questions

Is this a pre-workout?

A light one. 100mg of caffeine and no pump or endurance ingredients, so it's not comparable to Gold Standard Pre-Workout (175mg caffeine, 3g creatine, beta-alanine and citrulline). Amino Energy suits an easy session or someone who wants a light lift; a dedicated pre-workout suits heavy training.

Can I drink it on rest days?

Yes — that's one of its main uses. At 10 calories it's a straightforward energy drink replacement.

Does it replace protein powder?

No. 5g of free-form aminos is not the same as 24g of complete protein. Amino Energy supplements around a diet that already has enough protein in it.

How much caffeine is safe in a day?

Most healthy adults tolerate up to about 400mg. Two serves of Amino Energy is 200mg, which leaves room for coffee — but count everything, including any pre-workout.

Can I take it fasted?

Yes, and it's one of the better use cases. At 10 calories it won't meaningfully break a fast, and the aminos give your body something to draw on during a fasted session.