Some oils can be harmful to your body, particularly when consumed in excess or if they contain unhealthy fats. Here are some types of oils that are considered harmful:

### 1. **Trans Fats:**
- **Partially Hydrogenated Oils:** These are industrially processed oils that contain trans fats, which are harmful to heart health. They raise bad cholesterol (LDL) and lower good cholesterol (HDL).
- **Examples:** Margarine, shortening, and some processed and fried foods.

### 2. **Highly Refined Vegetable Oils:**
- **Examples:** Soybean oil, corn oil, and canola oil when highly processed. These oils can be high in omega-6 fatty acids, which, when consumed in excess, can promote inflammation and contribute to chronic diseases like heart disease.
- **Note:** Unrefined versions of these oils, when consumed in moderation, may have fewer health risks.

### 3. **Palm Oil:**
- Often used in processed foods, palm oil is high in saturated fat, which can raise LDL cholesterol levels when consumed in excess. While not as harmful as trans fats, excessive consumption can still negatively affect cardiovascular health.

### 4. **Cottonseed Oil:**
- This oil is high in omega-6 fatty acids and may contain pesticide residues due to the way cotton is grown, which may pose additional health risks.

### 5. **Butter and Lard (in Excess):**
- While natural fats like butter and lard are less harmful than trans fats, they are high in saturated fat. When consumed in excess, they can increase cholesterol levels and contribute to heart disease.

### 6. **Reheated Cooking Oils:**
- Reusing oils for frying at high temperatures can cause the oils to break down and produce harmful compounds like aldehydes, which have been linked to cancer and other diseases.

It's important to focus on using healthier oils like olive oil, avocado oil, and other oils rich in monounsaturated and polyunsaturated fats while minimizing the consumption of harmful oils.