Optifast Diet Reviews: Real Results, Side Effects & User Experiences

If you’ve ever wondered whether the Optifast diet really works, you’re not alone. Many people turn to this medically supervised program for weight loss, and it’s known for its meal replacement shakes and very low-calorie approach.

The Optifast diet can help people lose weight quickly and safely when followed with proper medical support. It’s designed not just for fast results but for building healthy habits that last.

What makes Optifast stand out is the structure it offers. The program breaks down into phases, starting with an intense low-calorie stage focused on shakes and soups, then moving to a transition phase where you slowly add regular foods back into your diet.

This method is guided by health professionals, which means we’re not just guessing—we’re being monitored for safety and success. We’ll take a closer look at what this diet involves, what people are saying about it, and how the products fit into daily life.

If you’re considering Optifast or just curious about meal replacement plans, understanding what to expect can make all the difference.

What Is the Optifast Diet?

The Optifast diet is a medically supervised weight loss program that uses meal replacements to help people lose weight safely and quickly. It focuses on a very low-calorie diet (VLCD) combined with medical support and lifestyle changes.

The program is designed to guide us through different phases of weight loss, transition, and maintenance for long-term success.

How the Optifast Diet Works

Optifast works by replacing traditional meals with specially designed shakes, bars, and soups that provide complete nutrition but very few calories. During the first phase, called Active Weight Loss, we consume around 800 calories a day, mostly through Optifast products along with some low-starch vegetables and a little oil.

This helps us lose weight fast while getting enough nutrients. The program then shifts gradually to a transition phase where we start adding regular, low-calorie meals back into our diet.

Finally, we move to the maintenance phase, focusing on healthy eating habits and regular exercise, with no more meal replacements. This phased approach helps our bodies adjust and supports lasting weight control.

The Role of Medical Supervision

A key part of Optifast is the close involvement of healthcare professionals. Doctors, dietitians, and counselors monitor our progress and health throughout the program.

This keeps us safe, especially since very low-calorie diets like Optifast’s VLCD can be intense. Regular checkups help adjust the diet to our needs and address any side effects such as nausea or digestive changes.

Medical supervision also provides motivation and support, making it easier to stick with the plan and avoid risks related to rapid weight loss.

Who Is Optifast Best For?

Optifast is mainly designed for adults and teens with a body mass index (BMI) of 30 or higher, meaning it’s best for people with obesity who need to lose a significant amount of weight. It’s also often recommended for those preparing for weight loss surgery, as it can reduce weight safely before the operation.

Because of its strict nature, the program suits people who want medical guidance while dieting and can commit to following a structured plan. It’s not ideal for casual or light dieting since it requires medical visits and a strong commitment to replace most meals initially.

Optifast Diet Phases & Method

The Optifast diet follows a clear step-by-step plan designed to help us lose weight safely and keep it off. It starts with a strict low-calorie phase and slowly brings in real food again.

Along the way, medical check-ins and counseling support us.

Active Weight Loss Phase

This first phase is the most intense. We rely mostly on Optifast meal replacements — like shakes and bars — to get all our nutrients with very few calories, usually around 800 to 1,200 per day depending on our starting weight.

Doctors monitor us regularly here to watch our health and adjust meds if needed. We use five to six meal replacements a day for about 12 to 16 weeks.

This helps create a strong calorie deficit that leads to fast weight loss. We also take part in weekly group sessions that teach behavior changes, portion control, and physical activity.

Transition Phase

After losing weight, we don’t jump straight back to normal eating. Instead, this phase slowly brings real foods back into our diets while still using meal replacements.

This gradual reintroduction lasts until about week 26. The goal here is to prevent weight regain while our bodies adjust.

We start adding lean proteins, non-starchy veggies, and small meals as we reduce meal replacement use. Our counseling sessions continue to focus on food choices, meal timing, and portion size.

Staying active remains important. Overall, this phase helps us learn how to eat in a balanced way while keeping the weight off.

Maintenance Phase

Once we reach a stable weight, the maintenance phase begins. This lasts from week 27 to week 52 or longer and focuses on keeping the lost weight off for good.

We reduce the number of meal replacements to one or two per day, sometimes none. Calories increase slowly to meet our new weight maintenance needs.

Counseling sessions become less frequent but still provide important support for healthy habits and staying active. Medical visits keep checking our progress and health markers.

This phase is about long-term lifestyle changes and avoiding the pitfalls that cause weight regain.

Optifast Products & Meal Replacements

Optifast relies heavily on meal replacement products that are high in protein and low in calories. These products come in different forms like shakes, soups, and bars, designed to offer convenience and nutrition.

The line also includes key vitamins and minerals to support health during the diet.

Meal Replacement Shakes

Optifast meal replacement shakes are the core of the program. They provide about 200 calories per serving and include around 26 grams of protein.

This high protein helps keep us feeling fuller longer and supports muscle maintenance while losing weight. The shakes come in ready-to-drink bottles or powder forms we can mix at home.

Milk protein concentrate and soy protein isolate are the main protein sources. While some might find the texture a bit grainy, these shakes are designed to offer balanced nutrition.

Using the shakes is simple. During the active phase, we usually have 4 to 5 shakes daily.

They replace traditional meals and help reduce calorie intake safely under medical supervision.

Soups and Bars

Alongside shakes, Optifast offers soups and bars as meal replacement options. Soups are low-calorie, easy to prepare, and can add variety to the diet, especially when we need a warm meal.

The bars provide a quick snack or meal substitute. They are high in protein and fortified with vitamins and minerals like the shakes.

Both soups and bars help us stay on track without feeling deprived. These products are portion-controlled and fit into the calorie limits of the program.

They’re convenient for busy days when making a full meal isn’t practical.

Vitamins and Nutrient Content

All Optifast meal replacement products contain added vitamins and minerals. They include essential nutrients to mimic a balanced diet since we rely mainly on these products during the program.

Each serving covers 100% of daily values for key vitamins like A, C, D, and minerals such as calcium and iron. This helps prevent nutrient gaps often seen in strict low-calorie diets.

Because the diet is very low in calories, these fortified nutrients support overall health and energy. It’s crucial we follow the program’s advice, including any extra vitamin supplements recommended by health professionals.

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Recipe Card: Optifast Shake Mix

• Prep time: 2 minutes
• Tools: Blender or shaker bottle
• Ingredients:
  • 1 scoop Optifast powder (30g)
  • 8 fl oz water or milk (240 ml)
• Nutrition: ~200 calories, 26g protein, 12g carbs
• Instructions:
  1. Add powder to bottle.
  2. Pour in liquid.
  3. Shake or blend until smooth.
  4. Drink immediately or chill.

Ingredients Inside Optifast

The Optifast diet is built around carefully chosen ingredients to give us protein, carbs, vitamins, and minerals in a controlled way. This helps keep us full and nourished while sticking to low calories.

The shakes and meals use a mix of proteins, sweeteners, and added nutrients that work together to support weight loss.

Protein Sources

Optifast uses mostly milk proteins like calcium caseinate and sodium caseinate. These are good quality proteins that help keep muscle mass while losing fat.

Some versions also include milk protein concentrate, which adds more protein per serving. These proteins digest slowly to keep us feeling fuller longer.

There’s no soy protein isolate in the standard products, but the focus stays on dairy-based proteins. Protein is a key part in each shake, usually providing around 20 grams per serving.

Tip: We have a review on gut-friendly protein powders here – plus tips for better digestion.

This helps with muscle support, especially when calories are low.

Carbohydrates and Sweeteners

The carb part mainly comes from maltodextrin, a type of starch that gives us energy without causing spikes in blood sugar. There’s also lactose from the milk powder, which adds natural sugars.

Sweeteners like aspartame and acesulfame potassium are used instead of sugar to keep the shakes tasting good but low in sugar content. Fiber sources like fructo-oligosaccharides and inulin are added to help digestion and add a feeling of fullness.

Micronutrients and Additives

Optifast is packed with a wide range of vitamins and minerals to cover daily needs in a small amount of food. These include vitamins A, C, D, E, B-complex, plus minerals like calcium, magnesium, zinc, and iron.

You’ll also find small amounts of vegetable oils (like rapeseed and sunflower), medium-chain triglycerides (MCTs), and vegetable gums to improve texture. These ingredients help the shakes mix easily and have a smooth, pleasant mouthfeel – though we have to say these are not particularly healthy.

The products are designed to give us balanced nutrition while strictly controlling calories and sugar.

User Reviews and Results

Many people trying the Optifast diet share mixed experiences. Some celebrate steady weight loss and support from the program, while others mention challenges with sticking to the plan.

Clinical studies show promising short-term results, but long-term success often depends on follow-up care.

Weight Loss Success Stories

Several users report losing between 8 and 18 pounds within the first four weeks on the Optifast VLCD (very low-calorie diet). The rapid weight loss is often credited to the strict meal replacement plan, which limits calories to 800 or less daily during the active phase.

One common positive point is the weekly support through medical check-ins and group meetings. This helps participants stay motivated and handle cravings better.

Some people also say that the program taught them better eating habits for long-term weight control. The Optiwin clinical trial found that patients who followed the program strictly had significant weight loss and improvements in blood sugar and cholesterol levels.

Common Challenges and Complaints

Sticking to a diet mainly based on shakes, soups, and bars can be tough. Many users mention getting tired of the taste or feeling hungry between meals.

Some find the reliance on specific Optifast products limiting, especially when socializing or eating out. Side effects like nausea, stomach upset, and irregular bowel movements came up in reviews, mostly early in the diet.

These issues usually improve with time but can be discouraging. Cost is another concern.

The full program, including clinic visits and meal replacements, can be expensive. For example, a week’s supply of shakes may cost around $27 to $110 depending on the product type, making it a significant investment.

Comparing Clinical Trial Outcomes

Clinical trials, including the Optiwin study, back up many weight loss claims made by the Optifast program. Participants in these studies typically saw rapid weight loss, similar to user reports—often 2 to 5 pounds per week during the active VLCD phase.

Unlike many fad diets, Optifast trials emphasize medical supervision and behavior therapy, which help maintain weight loss long-term. Studies also show healthier improvements in cholesterol and glucose compared to slower diets.

Side Effects and Considerations

When starting the Optifast diet, it’s important to know what side effects might show up, how to handle common issues like nausea and hunger, and who really should steer clear of this program. Paying attention to these details helps us make safer, smarter choices for our health.

Possible Side Effects

Some of the most common side effects from the Optifast diet include nausea, upset stomach, and changes in bowel movements. These usually come from switching to a very low-calorie meal replacement diet, which is different from regular eating habits.

Because Optifast is low in calories—often under 800 per day during the first phase—our bodies can react with these mild symptoms. Fatigue or headaches can happen too, especially when our bodies adjust to the rapid weight loss.

We should keep in close contact with health professionals during the program. This helps catch any serious issues early and adjust the plan if needed.

Managing Nausea and Hunger

Nausea can be a big challenge on a liquid meal replacement diet like Optifast. One way we can manage it is by drinking plenty of water throughout the day.

This can help reduce queasiness and keep digestion moving. Eating the low-starch vegetables allowed in the program also helps.

They provide fiber and bulk, which can ease hunger and reduce discomfort. Small, frequent sips of Optifast shakes instead of gulping can make a difference in how we feel.

Hunger can spike, especially during the first weeks. Joining group meetings or counseling sessions helps us stay motivated and learn tricks to beat hunger, like drinking herbal teas or distracting ourselves with light activities.

Who Should Avoid Optifast?

Optifast is not for everyone. We should avoid this program if we’re pregnant, breastfeeding, or have serious health conditions like uncontrolled diabetes, heart problems, or kidney disease.

The very low-calorie diet can be too harsh or unsafe in these cases. Kids under 18 generally aren’t recommended for this diet unless supervised closely by a healthcare provider.

If we have a history of eating disorders, a meal replacement diet focused on rapid weight loss could trigger unhealthy behaviors. In these situations, a more traditional, balanced diet might work better.

Always talk to a doctor before starting.

Cost, Support, and Alternatives

When we look at the Optifast diet, it’s clear that the price, support system, and other available weight loss options are important. Knowing what we pay for, how help is given, and what else is out there can make a big difference in choosing the right path.

Program Costs and Value

Optifast isn’t cheap. The program can run several hundred to over a thousand dollars a month, depending on how many meal replacements and doctor visits we need.

This includes shakes, bars, and soups plus the medical check-ins. What’s covered usually includes full medical support, which sets it apart from simpler diets that only sell food.

For some, paying more is worth it because of the structure and supervision. But it might not fit smaller budgets, and some find other plans cheaper.

We might compare Optifast costs to programs like Nutrisystem or Jenny Craig, which often cost less but don’t include as much medical oversight. Knowing the total price helps us decide if this investment matches our weight loss goals.

Group-Based Behavior Therapy

Support is a big part of Optifast, and group-based behavior therapy plays a key role. This means we join regular group sessions led by counselors or dietitians to discuss challenges, learn new habits, and stay motivated.

The group setting helps us share experiences and feel less alone. It’s designed to make lifestyle changes stick rather than just focus on quick weight loss.

Other Weight Loss Programs

There are many alternatives to Optifast if cost or program style doesn’t fit us. Noom, for example, offers app-based coaching focused on behavior changes and tracking food.

It’s often cheaper and more flexible but lacks the direct medical supervision Optifast provides. Other options like traditional diets (like keto or intermittent fasting) don’t usually provide structured support.

For those wanting meal replacements but at different prices, SlimFast or Artah Nutrition offer similar products. Medical weight loss treatments, such as gastric bypass or medications, might be necessary for some but often require doctor supervision before starting diets like Optifast.

Knowing what fits our budget, lifestyle, and health needs will guide us to the best choice.

Frequently Asked Questions

We often get questions about how much weight people lose, what side effects to expect, what the diet looks like, and how the shakes fit into daily life. Some also want to see real results or hear unusual stories from those on the program.

What’s the typical weight loss with Optifast after the first month?

Most people lose between 8.8 to 17.6 pounds (4 to 8 kg) in the first four weeks. That breaks down to losing about 2.2 to 4.4 pounds (1 to 2 kg) per week.

This is thanks to the very low-calorie diet the program uses.

What are some common side effects when starting Optifast?

Some people might feel nausea or have an upset stomach. Changes in bowel movements can also happen.

This is normal when switching to a low-calorie, meal-replacement diet, but it’s good to stay in touch with your health team.

Can I see before and after photos of people who’ve been on Optifast for 3 months?

Optifast shares success stories and photos on their official site and in some reviews. After three months, significant weight loss and body changes are often clear.

What’s in the Optifast diet plan for a beginner?

The beginner phase is called Active Weight Loss. It lasts around 12 weeks.

We focus mostly on meal replacements like shakes, soups, and bars, plus low-starch veggies and a little oil. Calories are kept below 800 per day at this stage.

How do Optifast shakes fit into the daily diet routine?

Typically, we have about five Optifast shakes a day during the first phase. These shakes replace regular meals and provide essential nutrients.

They make it easier to track calories and keep nutrition balanced.

Got any wild stories about experiences on the Optifast diet?

Some folks mention feeling shaky or very tired in the early days.

Others say the weekly group meetings really helped them stick with it.

There are even stories of people using Optifast before surgery and having smoother recoveries.